PLANTS MORPHOLOGY - a branch of botany - the science of plant forms. In all its vastness, this part of science includes not only the study of the external forms of plant organisms, but also the anatomy of plants (cell morphology) and their systematics (see), which is nothing more than a special morphology of various groups of the plant kingdom, starting from the largest to the smallest: species, subspecies, etc. The expression M. has been established in science mainly since the time of Schleiden's famous book - the foundations of botany ("Grundzuge der Botanik", 1842-1843). Plant forms are studied in mathematics, regardless of their physiological functions, on the basis that the form of a given part or member of a plant does not always have the same physiological significance.

So, for example, the root, which serves mainly to suck out liquid food and to strengthen the plant in the soil, is aerial and does not serve to strengthen it in the soil, but to absorb moisture and even carbon dioxide from the air (orchids; harpids, living on trees, etc.). ); it can also serve exclusively for hitching to solid soil (ivy); the stem, which in most plants serves to carry liquid food from the root to the rest of the plant, serves in some of them to absorb carbon dioxide from the air, that is, they take over the physiological administration of leaves, for example. in most cacti, devoid of leaves, in fleshy thrush, etc. Nevertheless, there is no way to completely digress from the physiological point of view when studying M., because only the physiological administration that has fallen to its lot can understand and explain the significance of the structure and form of a given plant member .

Thus, the allocation of M. in a special branch is based mainly on the property of the human mind itself, on logical necessity. From a morphological point of view, a plant, like an animal, does not consist of organs, but of members that retain the main features of their form and structure, regardless of the administration that may fall to their lot. The main theoretical principle of M. is the so-called motamorphosis of plants. This doctrine was expressed for the first time in a certain form by the famous Goethe in 1790, however, only in relation to higher flowering plants. This metamorphosis or transformation depends on the fact that all parts of each plant are built from the same organized material, namely from cells. Therefore, the shapes of the various parts fluctuate only between known, more or less wide limits. Surveying the whole multitude of plant forms, we discover that they are all built on the basis of two main principles, namely, the principle of repetition and the principle of adaptability. The first is that in every plant the same terms are indeed repeated. This applies to both the simplest, elementary members, and the most complex ones. First of all, we see the repetition of the cells themselves: the whole plant consists of cells, then the repetition of tissues: we meet the same tissues everywhere, and in the root, and in the stem, and in the leaf, etc. The same is observed with regard to the most complex members of the internode, node, leaf. Adaptability consists in the modification of repetitive terms in order to adapt to physiological functions and to environmental conditions. The combination of these two principles determines what is called motamorphosis. Thus, the motamorphosis of plants is the repetition of members of a given order, changing on the basis of the principle of adaptability.

The study of M. and the establishment of both rules common to all plants in general M., and private rules relating to different orders of groups of the plant kingdom in a particular or special M., is carried out using the following methods:

1) comparison of finished heterogeneous members of the same and different plants according to their external and internal structure;

2) developmental history or embryology,

3) the study of deviant or ugly forms (plant teratology).

The most fruitful of these methods is the embryological method, which has yielded the most important results, especially with regard to lower and spore-bearing plants in general.

Plants, like all living things, are made up of cells. Hundreds of cells of the same shape and with the same function form a tissue; an organ consists of several tissues. The main organs of the plant are the roots, stem and leaves, each of them performs a very specific function. Important reproductive organs are flowers, fruits, and seeds.

The roots have two main functions: the first is to nourish the plant, the second is to fix it in the soil. Indeed, the roots absorb water and mineral salts dissolved in it from the ground, thus they provide a constant supply of moisture to the plant, which is necessary both for its survival and for its growth. That is why it is so important that the plant does not wither or dry out, water it regularly in hot and dry times.

The externally visible part of the root is the smooth, hairless growing part in which the maximum growth occurs. The growing point is covered with a thin protective sheath, the root cap, which facilitates root penetration into the ground. The suction zone, located near the point of growth, is designed to absorb water and mineral salts needed by the plant, it is covered with a thick down, which is easy to see with a magnifying glass and which consists of the thinnest roots called root hairs. The conductive zone of the roots performs the function of transferring batteries. In addition, they also have a support function, they firmly fix the plant in the soil. The shape, size, structure and other features of the roots are closely related to these functions and, of course, change depending on the environment in which they have to develop. Usually the roots are underground, but there are water and aerial ones.

The roots, even in plants of the same species, are of very different lengths, which depend on the type of soil and the amount of water it contains. In any case, the roots are much longer than we think, especially if we take into account the thinnest root hairs, whose purpose is to absorb; in general, the root apparatus is much more developed than the aerial part of the plant located on the surface of the earth.

The main functions of the stem are to support the aerial part and the connection between the root system and foliage, while the stem regulates the uniform distribution of nutrients throughout all the internal organs of the plant. On the stem, where the leaves are attached, sometimes quite noticeable thickenings are visible, which are called nodes, the part of the stem between two nodes is called the internode. The stem, depending on its density, has different names:

The stem, if not very dense, as in most herbaceous plants;

Straw, if it is hollow and divided, like in cereals, by clearly visible knots. There is usually a lot of silica in such a stem, which increases its strength;

The trunk, if woody and branched, like most trees; or woody, but not branched, with leaves at the top, like palms.

Depending on the density of the stem, plants are divided into:

Herbaceous, which have a delicate, not lignified stem;

Semi-shrub, in which the stem lignifies the trunk only at the base;

Shrub, in which all branches are lignified, branching from the very base;

Woody, in which the trunk is completely lignified, it has a central axis (the trunk itself), branching only in the upper part.

Depending on the lifespan that is associated with the life cycle, herbaceous plants are usually classified as follows:

Annuals, or annuals, if they grow only one year, and die after they have flowered, produced fruit, and dispersed seeds;

Biennials, or biennials, if they grow for two years (usually in the first year they have only a rosette of leaves, in the second year they bloom, bear fruit, then dry up);

Perennials, or perennials, if they live for more than two years, usually bloom and bear fruit every year, and "rest", that is, in cold or dry times, the above-ground part of the plant dies off, but the underground part of the plant remains alive. There are plants in which part of the stem can change and turn into a real storage organ. Usually these are underground stems that serve for vegetative propagation, as well as for the preservation of the plant in an unfavorable period for growth. The most famous of them are tubers (like potatoes), rhizomes (iris) and bulbs (narcissus, hyacinth, onion).

Leaves have many different functions, the main one is the already mentioned photosynthesis, that is, a chemical reaction in the leaf tissue, with the help of which not only organic substances are created, but also oxygen, which is necessary for life on our planet. Usually the leaf consists of a petiole, a leaf blade more or less wide, which is supported by veins, and stipules. The petiole connects the leaf to the stem. If there is no petiole, then the leaves are called sessile. Inside the leaf are vascular fibrous bundles. They continue in the leaf blade, branching, form a dense network of veins (nervation), through which the plant juice circulates, in addition, they support the blade, giving it strength. Based on the location of the main veins, there are different types of venation: palmate, pinnate, parallel and arcuate. The leaf blade, depending on which plant it belongs to, has a different density (hard, juicy, etc.) and completely different shapes (rounded, elliptical, lanceolate, arrow-shaped, etc.). And the edge of the leaf blade gets its name depending on its structure (solid, serrated, serrated, lobed, etc.). If the notch reaches the central vein, then the lobes become independent and can take the form of leaflets, in which case the leaves are called complex, they, in turn, are divided into palmate-complex, pinnate-complex, and so on.

The beauty and originality of the shapes and colors of flowers have a very definite purpose. With all this, that is, tricks and devices developed over the centuries, nature from time to time supplies the flower only so that its genus continues. A flower, which has both male and female organs, must undergo two most important and necessary processes in order to achieve this goal: pollination and fertilization. Usually, in higher plants, the flowers are bisexual, that is, they have both male and female organs. Only in some cases the sexes are separated: in dioecious, for example, in willow, holly, and laurel, male and female flowers are on different specimens, and in monoecious, for example, in corn and pumpkin, both male and female flowers are separately placed on the same plant. In fact, all the parts that make up a flower are various modifications of the leaf that have occurred in order to perform various functions.

Above the peduncle, you can see a thickening called the receptacle, on which different parts of the flower are located. The double, or simple, perianth is the outer and most striking part of the flower, the perianth in the truest sense of the word covers the reproductive organs and consists of a calyx and a corolla. The calyx consists of leaflets, usually green, called sepals, their task, especially during the period when the flower is in bud, is to protect the internal parts. When the sepals are soldered together, like in a carnation, the calyx is called sympetalous, and when they are separated, for example, like in a rose, the calyx is separate-petal. The calyx rarely falls off, and in some cases it not only remains, but also grows in order to better fulfill its protective function. Corolla - the second element of the perianth - consists of petals, usually brightly colored and sometimes pleasantly smelling. Their main function is to attract insects in order to facilitate pollination and, accordingly, reproduction. When the petals are more or less soldered together, the corolla is called cleavage, and if they are separated, then separate petal. When there is no obvious difference between calyx and corolla, as, for example, in a tulip, the perianth is called simple corolla, and the flower itself is simple. The reproductive male apparatus of a flower, or androecium, consists of a variable number of stamens, consisting of a sterile, thin and elongated stamen called a stamen filament, at the top of which is an anther, it contains pollen sacs. Pollen, the fertilizing male element, is usually yellow or orange in color.

The reproductive female apparatus of a flower, or gynoecium, is formed by one or more pistils. Each of them consists of a lower hollow and swollen part, called the ovary, containing one or more ovules, the upper filiform part is called the column, and its top, designed to collect and hold pollen grains, is called the stigma.

Flowers on a plant can be located one at a time, at the top or in the axils of the branches, but more often they are combined into groups, the so-called inflorescences.

Among the inflorescences, the most common are the following: inflorescences formed by flowers on pedicels: a brush, for example, wisteria, panicle (lilac), umbrella (carrot) and shield, like a pear. Inflorescences formed by stemless, that is, sessile flowers: ear (wheat), earring (hazel), basket (daisy).

Pollination

Very often, wind, water, insects and other animals take an unwitting part in the most important operation of pollination, which is necessary for the propagation of plants. Numerous insects, such as bees, bumblebees and butterflies, in search of nectar, a sugary substance found in nectaries located in the inner part of many flowers, sit on the flowers. When they touch the stamens, pollen from the mature anthers falls on them, and they transfer it to other flowers, where the pollen falls on the stigma. This is how fertilization occurs. The bright color, attractive shape, and fragrance of flowers have a very definite function of attracting pollinating insects that carry pollen from one flower to another.

Pollen, especially very light, which is very abundant in plants with small flowers without a corolla, and therefore not attractive to insects, is also carried by the wind. It is this pollen, carried in large quantities through the air, that is the cause of most spring allergies.

Fruits and seeds

After fertilization, the walls of the ovary undergo profound changes, become lignified or fleshy, they form a fruit (or pericarp, testis), at the same time, ovules develop. Accumulating a supply of nutrients, they turn into seeds. Often, when the fruit is ripe, it is tasty, fleshy, brightly colored and smells good. By this he attracts animals, by eating him, they help spread the seeds. If the fruit is not brightly colored and not fleshy, then its seeds will spread differently. For example, the fruit of the meadow dandelion has light fluffs, resembling a small parachute, and the fruits of maple and linden have wings and are easily carried by the wind; other fruits, such as burdock, have hooks with which they cling to the wool of sheep and to human clothing.

Among the fleshy fruits, the most famous are the drupe, inside it there is one seed protected by the pericarp (cherry, plum, olive), and a berry, in which there are usually many seeds and they are immersed directly in the pulp (grapes, tomato).

Dry fruits are usually divided into open (crack) and non-open (non-crack) depending on whether they open on their own when ripe or not. For example, the first group includes beans, or legume pods (peas, beans), leaflets (levkoy, radish, beetroot), box (poppy) and achene (wrestler). In the fruits of the second group there is always one seed, practically soldered to the fruit itself. The most famous examples are the weevil in cereals, the lionfish in maple and elm, and the achene with tufted in Compositae.

Inside the fruit is a seed in which there is an embryo, practically a future plant in miniature. Once in the soil, where the seed can germinate, it leaves the state of dormancy, in which it can sometimes remain even for several years, and begins to sprout. Thus, the seed completes its function, that is, the protection and nutrition of the sprout, which could not exist independently, and a new life begins.

Under the outer protective layer, called the peel (shell), a stalk with two germ layers, called cotyledons, is clearly visible, they have a large supply of nutrients, a root and an ovule (ovule).

During germination, the seed undergoes various changes: first, a root develops, which lengthens in the ground, and then a small bud, the cotyledons gradually give up their reserves and little by little the plant begins to take its shape, developing three main organs - root, stem and leaf.

Form of shoot, or long leaves (in ferns). 2. Experimental work on the formation of educational activities in the process of studying the morphology of ampelous plants in biology lessons 2.1 Methods for studying ampelous plants in a school biology course Objectives of the lesson: to form the concept of a stem as the axial part of a modified shoot of ampelous plants. Explore the relationship between...

In the Middle Ages, a utilitarian approach to the classification of organisms prevailed. For example, plants were divided into agricultural, food, medicinal and ornamental. When classifying plants, the features of the external structure of their generative organs were taken into account. For example, the Italian Andrea Cesalpino was guided by the characteristic features of seeds and fruits, the Frenchman Joseph Tournefort considered the determining form ...

Heaps of numerous systematic and unsystematic studies in hitherto unknown area of ​​knowledge about the structure of plant bodies, the area to which he gave the name "morphology". The basis of the new doctrine of plant metamorphosis created by Goethe was his statement about the transformation of some plant organs into others and about the existence of one initial organ, the transformation of which forms ...

Berries 0.2-0.3g. Up to 3 berries are formed in the inflorescence. Blooms in June, July. Fruits in September (Rabotnov T.A., 1978). Chapter III. Morpho-anatomical and ecological features of the structure of psychrophytic plants of the heather family Heather are widely distributed around the globe, most representatives of heather are shrubs or shrubs, sometimes grasses, but among them there are also large ...

graduate work

1.1 Concept, essence, goals, objectives, basic principles of plant morphology

Morphology of plants, phytomorphology - the science of the patterns of structure and processes of shaping of plants in their individual and evolutionary-historical development. One of the most important branches of botany. With the development of plant morphology, plant anatomy, which studies the tissue and cellular structure of their organs, plant embryology, which studies the development of the embryo, and cytology, the science of the structure and development of cells, emerged from it as independent sciences. Thus, plant morphology in the narrow sense studies the structure and morphology, mainly at the organismal level, but its competence also includes consideration of the patterns of the population-species level, since it deals with the evolution of form.

The main problems of plant morphology: revealing the morphological diversity of plants in nature; studying the regularities of the structure and mutual arrangement of organs and their systems; studies of changes in the general structure and individual organs during the individual development of a plant (ontomorphogenesis); clarification of the origin of plant organs during the evolution of the plant world (phylomorphogenesis); study of the impact of various external and internal factors on shaping. Thus, not limited to the description of certain types of structure, plant morphology seeks to elucidate the dynamics of structures and their origin. In the form of a plant organism and its parts, the laws of biological organization are externally manifested, i.e. internal interconnections of all processes and structures in the whole organism.

In the theoretical morphology of plants, two interrelated and complementary approaches to the interpretation of morphological data are distinguished: identifying the causes of the emergence of certain forms (in terms of factors directly affecting morphogenesis) and elucidating the biological significance of these structures for the life of organisms (in terms of fitness) , which leads to the preservation of certain forms in the process of natural selection.

The main methods of morphological research are descriptive, comparative and experimental. The first is to describe the forms of organs and their systems (organography). The second is in the classification of descriptive material; it is also used in the study of age-related changes in the organism and its organs (comparative ontogenetic method), in elucidating the evolution of organs by comparing them in plants of different systematic groups (comparative phylogenetic method), in studying the influence of the external environment (comparative ecological method). And, finally, with the help of the third - experimental - method, controlled complexes of external conditions are artificially created and the morphological reaction of plants to them is studied, internal relationships between the organs of a living plant are studied.

Plant morphology is closely related to other areas of botany: paleobotany, plant systematics and phylogeny (the form of plants is the result of a long historical development, reflects their relationship), plant physiology (dependence of form on function), ecology, plant geography and geobotany (dependence of form on the external environment). ), with genetics (inheritance and acquisition of new morphological characters) and crop production.

Plant morphology is the science of plant forms. In all its vastness, this part of science includes not only the study of the external forms of plant organisms, but also plant anatomy (cell morphology) and their systematics, which is nothing more than a special morphology of various groups of the plant kingdom, from the largest to the smallest: species, subspecies, etc.

The expression "morphology" has established itself in science mainly since the time of Schleiden's famous book - the foundations of botany ("Grundzuge der Botanik", 1842-1843). In morphology, the forms of plants are studied, regardless of their physiological functions, on the basis that the form of a given part or member of a plant does not always have the same physiological significance.

So, for example, the root, which serves mainly for sucking out liquid food and for strengthening the plant in the soil, is airy and serves not to strengthen in the soil, but to absorb moisture and even carbon dioxide from the air (orchid; arfid, living on trees, etc.). ); it can also serve exclusively for hitching to solid soil (ivy); the stem, which in most plants serves to carry liquid food from the root to the rest of the plant, in some plants serves to absorb carbon dioxide from the air, i.e. takes over the physiological administration of leaves, for example, in most cacti, devoid of leaves, in fleshy milkweeds, etc. a member can only be a physiological function that has befallen him. Thus, the allocation of plant morphology to a separate branch is based mainly on logical necessity.

From a morphological point of view, a plant, like an animal, does not consist of organs, but of members that retain the main features of their form and structure, despite the administration that may fall to their lot.

The main theoretical principle of morphology is the so-called plant metamorphosis. This doctrine was expressed for the first time in a certain form by Goethe in 1790, however, only in relation to higher flowering plants. Metamorphosis, or transformation, depends on the fact that all parts of each plant are built from the same organized material, namely cells. Therefore, the shapes of the various parts fluctuate only between known, more or less wide limits.

Surveying the whole multitude of plant forms, we discover that they are all built on the basis of two main principles, namely, the principle of repetition and the principle of adaptability.

The first is that in every plant the same terms are indeed repeated. This applies to both the simplest, elementary members, and the most complex ones. First of all, we see the repetition of the cells themselves: the whole plant consists of cells.

Then there is the repetition of tissues: we find the same tissues everywhere, in the root, in the stem, in the leaf, and so on. The same is observed with regard to the most complex members of the internode, node, leaf.

Adaptability consists in the modification of repetitive terms in order to adapt to physiological functions and to environmental conditions. The combination of these two principles determines what is called metamorphosis.

Thus plant metamorphosis is the repetition of members of a given order, changing on the basis of the principle of adaptability. The study of morphology and the establishment of both rules common to all plants in general morphology, and particular rules relating to different orders of groups of the plant kingdom in particular or special morphology, is carried out using the following methods:

1) comparison of finished heterogeneous members of the same and different plants according to their external and internal structure;

2) developmental history or embryology,

3) the study of deviant or ugly forms (plant teratology).

Metamorphoses are called hereditarily fixed modifications of organs associated with a change in their main functions. The metamorphoses of the vegetative organs of plants are extremely diverse.

Escape metamorphoses

The shoot is the most variable organ of the plant. It is characterized by such properties as:

multifunctionality;

lability of behavior;

plastic.

Already in the first approximation, shoots are divided into two types:

1) vegetative

2) generative.

There is a distinct change in growth forms and shoot functions in the course of its biological development. For example:

Capturing a new area (lash or rhizome);

Enhanced nutrition (socket stage);

Formation of flowers and fruits (generative stage).

Let us consider the main types of specialized and metamorphosed organs of shoot origin.

In many ampelous plants, initially the entire shoot is above ground. It bears both scale-like and green rosette leaves. In the future, the leaves die off, and the stem part is drawn into the soil, where it thickens due to the deposition of reserve substances and turns into a rhizome.

Thus, two phases can be distinguished in the structure of the shoot: aboveground and underground. In the course of ontogenesis, the shoot undergoes a real transformation, metamorphosis in the literal sense. Such rhizomes are called submerging or epigeogenic - aboveground. Such a picture is observed during the formation of rhizomes: cuffs, gravel, strawberries, lungwort and others.

In other plants, the rhizome begins its growth phase from a bud that is underground. Such rhizomes of initially underground origin are called hypogeogenic. They are observed in very many perennial herbs and shrubs: wheatgrass, crow's eye, kupena, Veronica long-leaved and others.

In this case, the rhizomes are thin and serve more for vegetative propagation.

Metamorphoses of shoots are also stolons and tubers.

Tubers are thickenings of an underground shoot like potatoes, Jerusalem artichoke. Tuberous thickenings begin to develop at the ends of the stolons. Stolons are short-lived and are usually destroyed during the growing season, this is how they differ from rhizomes.

The leaves on the tuber fall off very early, but leave scars in the form of the so-called tuber eyes. In each eye there are 2-3 axillary buds, of which only one germinates. Under favorable conditions, the buds germinate easily, feeding on the reserve substances of the tuber and grow into an independent plant.

Thus, the third leading function of shoots is vegetative renewal and reproduction.

Some plant species form very peculiar leafy tubers (for example, thin-leaved core). These are modified leaf blades sitting on petioles of rhizomes. These leafy tubers have lobes, pinnate venation, and even mesophilic tissue, but are chlorophyll-free and adapted to store starch storage.

Metamorphoses of stems and leaves are most pronounced in succulent plants.

Succulents are plants that have succulent, fleshy leaves or stems that serve as a kind of reservoir for storing moisture. Succulents use this moisture very carefully and economically during the dry period. Succulents are divided into two large groups:

Stem succulents - have fleshy stems, the leaves, as a rule, have turned into spines (to reduce transpiration). As examples of stem succulents, we can name the well-known American cacti and African spurges that are very similar to them.

Leafy succulents have thick, fleshy leaves. These include Crassula: stonecrop, golden root; liliaceae, amaryllis, agave, aloe, gasteria, haworthia.

Many plants have a wide variety of thorns and spines, which, moreover, have a different origin. For example, in cacti and barberries, the spines are modified leaves. Typically, such spines are intended primarily to reduce transpiration, while the protective function in most cases is secondary.

Other plants have spines of shoot origin - these are modified shortened shoots. Often they begin to develop as normal leafy shoots, and then become woody and lose their leaves.

A further step in the underdevelopment of leaves and the transfer of their functions to green stems leads to the formation of such metamorphosed organs as phyllocladia and cladodia.

Phyllocladia (Greek phyllon - leaf, clados - branch) are flat, leaf-like stems and even entire shoots. The most famous example of plants with metamorphoses of this kind are needles (Ruscus). It is very interesting that scaly leaves and inflorescences develop on the leaf-like shoots of the butcher's broom, which never happens on normal leaves. In addition, phylloclades, like leaves, have limited growth.

Flattened stems are also called cladodia, which, unlike phyllocladia, have retained the ability for long-term growth. These are quite rare modifications and are found, for example, in the Australian Mühlenbeck.

In many climbing plants (peas, ranks, pumpkins, etc.), leaves are modified into tendrils, which have the ability to twist around a support. The stem of such plants is usually thin and weak, unable to maintain an upright position.

Creeping plants (strawberries, stone berries, etc.) form a special type of shoots that serve for vegetative reproduction, such as whips and stolons. They are classified as aerial creeping plants.

Thus, the morphological features of ampelous plants are reduced, first of all, to a certain form of shoots (hanging, climbing).

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Plant morphology

phytomorphology, the science of the patterns of structure and processes of plant formation in their individual and evolutionary-historical development. One of the most important branches of botany (See Botany). As M.'s development r. from it stood out as independent sciences Plant anatomy , studying the tissue and cellular structure of their organs, Plant Embryology , studying the development of the embryo, and Cytology - the science of cell structure and development. Thus, M. r. in a narrow sense, it studies the structure and shaping, mainly at the organismic level, however, its competence also includes consideration of the patterns of the population-species level, since it deals with the evolution of form.

Main problems and methods. The main problems of M. R.: the identification of the morphological diversity of plants in nature; studying the regularities of the structure and mutual arrangement of organs and their systems; studies of changes in the general structure and individual organs during the individual development of a plant (ontomorphogenesis); clarification of the origin of plant organs during the evolution of the plant world (phylomorphogenesis); study of the impact of various external and internal factors on shaping. Thus, without being limited to the description of certain types of a structure, M. r. seeks to elucidate the dynamics of structures and their origin. In the form of a plant organism and its parts, the laws of biological organization are externally manifested, that is, the internal interconnections of all processes and structures in the whole organism.

In theoretical M. r. distinguish between 2 interrelated and complementary approaches to the interpretation of morphological data: identifying the causes of the emergence of certain forms (in terms of factors directly affecting morphogenesis) and elucidating the biological significance of these structures for the life of organisms (in terms of fitness), which leads to preservation of certain forms in the process of natural selection.

The main methods of morphological research are descriptive, comparative and experimental. The first is to describe the forms of organs and their systems (organography). The second is in the classification of descriptive material; it is also used in the study of age-related changes in the organism and its organs (comparative ontogenetic method), in elucidating the evolution of organs by comparing them in plants of different systematic groups (comparative phylogenetic method), in studying the influence of the external environment (comparative ecological method). And, finally, with the help of the third - experimental - method, controlled complexes of external conditions are artificially created and the morphological reaction of plants to them is studied, and internal relationships between the organs of a living plant are also studied through surgical intervention.

M. r. is closely related to other sections of botany: paleobotany, plant systematics and phylogeny (the shape of plants is the result of a long historical development, reflects their relationship), plant physiology (dependence of form on function), ecology, plant geography and geobotany (dependence of form on the environment), with genetics (inheritance and acquisition of new morphological characters) and crop production.

Brief historical outline. The origins of M. R., like botanists in general, go back to ancient times. The terminology of morphological descriptions of plants was developed mainly in the 17th century; at the same time, the first attempts at theoretical generalizations were made (Italian scientists A. Cesalpino, M. Malpighi, German - I. Jung). However, M.'s formation r. As an independent science, it dates back to the end of the 18th century, when the book An Experiment on the Metamorphosis of Plants (1790) by I. W. Goethe appeared, who also proposed the term “morphology” itself (1817). Goethe emphasized the commonality in the variety of forms of plant organs and showed that all shoot organs, from cotyledons to parts of a flower, represent modifications (metamorphoses) of the same "in type" of an elementary lateral organ - a leaf. The reason for metamorphosis, according to Goethe, is a change in the nutrition of newly formed leaves as the top of the shoot moves away from the soil. Goethe's works had a decisive influence on the subsequent development of M. r. However, in the idea of ​​the “type” of the organ, which for Goethe himself was quite real, there was also the possibility of an idealistic approach, i.e., interpretation of it as an “idea” of the organ, embodied in various forms. Many followers of Goethe developed the comparative M. r. These are the first concepts of "phytonism", according to which the higher plant is a collection of individual plants - "phytons" (French scientist C. Gaudisho, 1841; German scientist K. Schulz, 1843), and ideas about the initially existing "ideal" three main plant organs (German botanist A. Braun, 50s of the 19th century) and others.

1st half of the 19th century characterized by M.'s flourishing river. O. P. Decandol (1827), independently of Goethe, came to the idea of ​​the unity of organs and their metamorphosis. R. Brown is the first to study the ovule in holo- and angiosperms; he discovered archegonia and spermatozoa in conifers. In the development of comparative M. r. A significant role was played by the German botanist A. Braun, who studied the nature of metamorphosed organs and, together with K. Schimper, created the doctrine of the mathematical laws of leaf arrangement (phyllotaxis). In the 1st half of the 19th century. the foundations of the ontogenetic and phylogenetic trends in M. were laid. An active promoter of the ontogenetic method was the German botanist M. Schleiden (1842-1848). The beginning of the development of phylogenetic M. r. It was established by the works of the German botanist W. Hofmeister (1849-51), who described the alternation of generations and proved the homology of the reproductive organs of lycopsids, ferns and gymnosperms. Thanks to this, it was possible to establish a morphological, and then an evolutionary relationship between spore and seed plants.

In the second half of the 19th and early 20th centuries. great influence on M.'s development. had the evolutionary theory of Ch. Darwin (see Darwinism). Evolutionary, or phylogenetic, M. r. was further developed in the works of Russian botanists I. D. Chistyakov, I. N. Gorozhankin and his school, German - N. Pringsheim, E. Strasburger and others, who developed the doctrine of the homology of the reproductive organs of different groups of plants and the cycles of their development . In this direction, the work of I. N. Gorozhankin on the development of Gametophyte a and fertilization in gymnosperms, by V. I. Belyaev, who studied the development of the male gametophyte in heterospores, and by S. G. Navashin’s discovery (in 1898) of double fertilization in flowering plants. The works of the Czech botanists L. Chelakovsky (1897-1903) and I. Velenovsky (1905-13) were of great importance. Another direction in evolutionary M. r. based mainly on the study of fossil plants. The works of the English botanist F. Bower (1890–1908, 1935), the German botanist G. Potonier (1895–1912), and the French botanist O. Lignier (1913–14) shed light on the fundamental questions of the origin of the main organs of higher land plants. These scientists showed 2 possible ways for the emergence of a leaf-stem structure: the formation of superficial lateral outgrowths (enations) on the primary leafless axis and the differentiation of the initial system of branching cylindrical homogeneous organs, in which part of the branches flattened and grew together with the formation of large flat leaves. These works predicted the structure of the oldest land plants, the psilophytes, discovered only in 1917. The ideas of Bower, Potonier, and Linier served as the basis for the telome theory formulated in 1930 by the German botanist W. Zimmermann. A big role in M.'s development of river. played by the Stelar theory of the evolution of the conducting system of higher plants, proposed by the French botanist F. van Tiegem (70s of the 19th century) and developed by the American - E. Jeffrey (1897) and his school. Some morphologists continued to develop "phytonistic" views on the structure of the body of plants, which acquired a materialistic and dynamic character (American botanist Asa Gray, Italian - F. Delpino, Czech morphologist I. Velenovsky, Russian - A. N. Beketov, French - G. Shovo) . Further rethinking of the concept of “phyton” as a metamer of a highly differentiated shoot organ led to a purely ontogenetic concept of it as a unit of growth (English - J. Priestley, 30s of the 20th century, Swiss - O. Schüpp, 1938, Soviet botanist D. A. Sabinin, 1963). Important achievements of evolutionary M. r. - theories of the origin of the flower: strobilar, formulated by the English botanists N. Arber and J. Parkin (1907), and pseudonymous, belonging to the Austrian botanist R. Wettstein (1908). The Russian botanist Kh. Ya. Gobi published the first evolutionary classification of fruits in 1921.

Ontogenetic M. r. in the post-Darwinian period developed in close contact with the phylogenetic and experimental. The German botanist A. Eichler studied the history of leaf development (1869) and the patterns of flower structure (1878-1882), the Russian botanist V. A. Deinega studied the ontogeny of leaves in monocotyledonous and dicotyledonous plants (1902). Extremely metamorphosed forms of plants were studied by the ontogenetic method by Russian morphologists N. N. Kaufman on cacti (1862), F. M. Kamensky on pemphigus (1877, 1886), and S. I. Rostovtsev on duckweeds (1902). In development of experimental M. of river. (the term was proposed by K. A. Timiryazev, 1890), a great contribution was made by A. N. Beketov, who considered the most important factors in the formation of the physiological function of plant organs and the influence of external conditions. The Russian botanist N. F. Levakovsky was one of the first to experimentally study the behavior of the shoots of a terrestrial plant in an aquatic environment (1863), the German physiologist G. Vöchting observed in an experiment (1878-82) the influence of various natural conditions on the shape and discovered the phenomenon of polarity in plants. The German botanists G. Klebs (1903) and K. Goebel (1908) showed in experiments the dependence of organ growth forms on specific factors - light, moisture, food - and obtained artificial metamorphoses. Goebel owns the multi-volume summary work "Organography of Plants" (1891-1908), where the description of organs is given in ontogeny, taking into account external conditions and with experimental verification of the causes of morphogenesis. In the field of experimental M. of river. The Austrian botanist Yu. Vizner (1874–89, 1902), the Czech botanist R. Dostal (a series of works on experimental shoot formation, since 1912), and others worked fruitfully. the works of the Soviet botanist N. P. Krenke (1928, 1950), who studied regeneration in plants and the patterns of age-related morphological changes in shoots and formulated the theory of “cyclic aging and rejuvenation” of plants (1940), adjoin.

Ecological M. r. originated simultaneously with the geography and ecology of plants. One of its main problems is the study of life forms (see Life form) of plants. The founders of this trend are the Danes E. Warming (1902-16) and K. Raunkier (1905-07), the German botanist A. Schimper (1898). Russian and Soviet botanical geographers and geobotanists intensively studied the features of adaptive structures and methods of renewal and reproduction of plants in different botanical and geographical zones and regions (A. N. Krasnov, 1888; D. E. Yanishevsky, 1907-12, 1934; G. N. Vysotsky, 1915, 1922-28; L. I. Kazakevich, 1922; B. A. Keller, 1923-33; V. N. Sukachev, 1928-38; E. P. Korovin, 1934-35; V. V. Alekhin, 1936, etc.).

Modern problems and directions of M. river. Descriptive M. r. retains its importance for systematics when compiling "Flora", determinants, atlases, reference books. The comparative morphological direction is represented by the works of V. Troll (Germany) and his school. He owns a major summary of the comparative morphology of higher plants (1935-39), a number of educational manuals and a multi-volume work on the morphology of inflorescences (1959-64). The English botanist A. Arber, while discussing comparative morphological data, came up with a peculiar theory of the origin of the leaf as an "incomplete shoot", close to the telome theory. The work (1952) of the Soviet botanist I. G. Serebryakov is devoted to the comparative morphology of the vegetative organs of higher plants on an ontogenetic and phylogenetic basis. Works on the structure and classification of fruits belong to the Soviet botanists N. N. Kaden (since 1947) and R. E. Levina (since 1956). Evolutionary M. r. was enriched by a new series of works by W. Zimmerman (1950-65), who developed the body theory he created and showed the close connection between phylogenetic "elementary processes" and ontogenesis. The Soviet botanist K. I. Meyer summed up the results of his study of the evolution of the gametophyte and sporophyte of higher spore plants and their organs (1958). He emphasizes the fruitfulness of the comparative morphogenetic method - comparing the morphological structures of living plants from groups of different evolutionary levels and constructing morphogenetic series that are not a series of ancestors-descendants, but demonstrating possible ways of transforming certain organs. Questions of the morphological evolution of angiosperms are being developed by the Soviet botanist A. L. Takhtadzhyan, who studies the relationship between ontogenesis and phylogenesis and develops in botany A. N. Severtsov’s theory of the modes of morphological evolution. A number of works on the evolution of the flower and the monograph "The Basic Biogenetic Law from a Botanical Point of View" (1937) belong to the Soviet botanist B. M. Kozo-Polyansky. A summary of the evolutionary morphology of flowering plants was published in 1961 by the American scientist L. Eames. The telome theory was continued to be developed by the French scientists P. Bertrand (1947), L. Amberger (1950-64) and others. With regard to the origin of the flower, many supporters of the telome theory expressed conflicting opinions. In the 40-50s. 20th century a discussion broke out between supporters of the classical strobilar theory of the origin of the flower (A. Eames, A. L. Takhtadzhyan, English botanist E. Korner, etc.) and representatives of the "new" telome morphology. As a result of the discussion, extreme views were sharply criticized and the positive aspects of the telome theory were clearly revealed, which convincingly depicts the course of evolution of vegetative organs. Many works are devoted to the origin of the peculiar morphological features of monocots, including cereals (A. Arber, A. Eames, M. S. Yakovlev, K. I. Meyer, L. V. Kudryashov, A. Jacques-Felix, and others).

The ontogenetic direction has largely merged with the experimental one and is intensively developing in contact with plant physiology (morphogenesis). An extensive summary of morphogenesis was made by the American biologist E. Sinnot (1960). Especially large is the series of works on the study of the growth cone of the shoot and root as the main sources of organogenesis and histogenesis in higher plants. Important theoretical generalizations in this area were made by the Swiss scientist O. Schüpp (1938), the American - A. Foster and his colleagues (1936-54), K. Esau (1960-65), the German - G. Guttenberg (1960-1961), the English - F. Clouse (1961). The regularities of the activity of the shoot tip in connection with general questions of the organization and evolution of plants are studied by the English botanist C. Wardlaw and his school (1952-69). In France, morphological work was greatly influenced by the new ontogenetic theory of leaf arrangement developed by L. Plantefol (1947), as well as the work of R. Buvat and his co-workers (50s). Laboratories of experimental M. of river work fruitfully. in a number of universities in France and in the scientific center in Orsay (R. Nozeran and others). The works of E. Bunning (Germany) are devoted to endogenous rhythms of morphogenesis. In the USSR, the most important work in the field of morphogenesis with the wide use of anatomical methods has been carried out since the 1940s. VK Vasilevskaya with employees (especially at facilities living in harsh environmental conditions); from the 50s - F. M. Kuperman with co-workers (the doctrine of the stages of organogenesis and their dependence on external conditions), as well as V. V. Skripchinsky with co-workers (the morphogenesis of herbaceous plants, in particular geophytes). Close to the morphogenetic direction of the work of physiologists - D. A. Sabinin (1957, 1963), V. O. Kazaryan with colleagues (since 1952). The works of N. V. Pervukhina and M. S. Yakovlev are mainly devoted to the morphogenesis of the flower and fruit. M. I. Savchenko, M. F. Danilova, and others. A series of works by I. G. Serebryakov and his school (since 1947) is devoted to the morphological aspects of shoot formation and the rhythms of the seasonal development of plants in different zones of the USSR. Morphological changes during the passage of plants through a long life cycle are studied on the basis of the age periodization developed by T. A. Rabotnov (1950) by the students and colleagues of I. G. Serebryakova and A. A. Uranov.

Ecological M. r. develops in terms of further regional description and classification of plant life forms, as well as a comprehensive study of their adaptation to extreme conditions: in the Pamirs (I. A. Raikova, A. P. Steshenko, etc.), in the Kazakh and Central Asian steppes, deserts and in mountainous regions (E. P. Korovin, M. V. Kultiasov, E. M. Lavrenko, N. T. Nechaeva), in the tundra and forest-tundra (B. A. Tikhomirov and coworkers), etc. Problems of classification and evolution life forms were multilaterally developed by I. G. Serebryakov (1952-64), who outlined the main direction of morphological evolution in the line from woody plants to herbaceous plants - a reduction in the life span of aboveground skeletal axes. His school conducts research on the evolution of life forms in specific systematic groups; this promising direction is also being developed by the school of the German botanist G. Meisel (GDR). The works of VN Golubev (1957) also belong to this area. An important basis for assessing the general directions of the evolution of life forms was provided by the work of the Englishman E. Korner (1949-55) and the Swiss E. Schmid (1956, 1963).

Significance for the national economy. Data of comparative, ecological and experimental M. of river. allow not only to understand the laws of shaping, but also to use them in practice. Works on ontomorphogenesis and ecological M. r. important for the development of the biological foundations of forestry and grassland farming, methods for growing ornamental plants, and recommendations for the rational use of wild-growing useful plants (medicinal, etc.), taking into account their renewal, and biological control over the growth of cultivated plants. Introductory work carried out in botanical gardens is based on the data of ontogenetic and ecological M. r. and at the same time provide material for new theoretical generalizations.

Congresses, congresses, press organs. Questions M. r. were repeatedly discussed at international botanical congresses, especially at the 5th (London, 1930), 8th (Paris, 1954), 9th (Montreal, 1959) and international symposia on individual problems (for example, on leaf growth - London, 1956). Colloquia are regularly collected on M. p. in France (for example, according to the structure of inflorescences - Paris, 1964; according to life forms - Montpellier, 1965; on general issues of structural organization - Clermont-Ferrand, 1969; on branching - Dijon, 1970). In the USSR, the problems of M. p. are discussed at congresses of the Botanical Society, at the All-Union Conference on Morphogenesis (Moscow, 1959), and at the All-Union Interuniversity Conference on M. r. (Moscow, 1968).

Works on M. r. published in the international journal Phytomorphology (Delhi, 1951). Collections of works of the Botanical Institute of the Academy of Sciences of the USSR in the series "Morphology and Anatomy of Plants" are regularly published in the USSR (since 1950); morphological works are published in the Botanical Journal (since 1916), Bulletin of the Moscow Society of Naturalists (since 1829), Scientific Reports of Higher School (since 1958), and other biological journals.

Lit.: Komarnitsky N. A., Morphology of plants, in the book: Essays on the history of Russian botany, M., 1947; Serebryakov I. G., Morphology of the vegetative organs of higher plants, M., 1952; Goethe I.V., Selected. op. in natural sciences, trans. [from German], M., 1957; Meyer K. I., Morphogeny of higher plants, M., 1958; Fedorov Al. A., Kirpichnikov M. E., Artyushenko Z. T., Atlas on descriptive morphology of higher plants, vol. 1-2, M., 1956-62; Serebryakov I. G., Ecological morphology of plants, M., 1962; Eames A.D., Morphology of flowering plants, trans. from English, M., 1964; Takhtadzhyan A. L., Fundamentals of the evolutionary morphology of angiosperms, M. - L., 1964; his, Origin and settlement of flowering plants, L. 1 1970; Göbel K., Organographie der Pflanzen, Tl 1-2, Jena, 1928-33; Troll W., Vergleichende Morphologic der höheren Pflanzen, Bd 1-2, B., 1935-39; his own, Praktische Einführung in die Pflanzenmorphologie, Tl 1-2, Jena, 1954-57; Wardlaw S., Organization and evolution in plants, L., 1965.

T. I. Serebryakova.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what "Plant Morphology" is in other dictionaries:

The science of the regularities of the structure and processes of plant shaping. In a broad sense, M. r. studies forms at all levels from the whole plant to cellular organelles and macromolecules, in a narrower sense only macrostructures. In this case, it stands out ... Biological encyclopedic dictionary

Morphology (in biology) studies both the external (shape, structure, color, patterns) of an organism, taxon or its constituent parts, and the internal structure of a living organism (for example, human morphology). It is divided into external morphology (or ... ... Wikipedia

Branch of botany, the science of plant forms. In all its vastness, this part of science includes not only the study of the external forms of plant organisms, but also the anatomy of plants (cell morphology) and their systematics (see), which ... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

plant morphology- section of botany; a science that studies the patterns of plant structure and the processes of morphogenesis in their ontogenesis and phylogenesis ... Plant anatomy and morphology

PLANT MORPHOLOGY- a branch of botany that studies the patterns of structure and processes of morphogenesis in plants in their ontogenesis and phylogenesis ... Glossary of botanical terms

Questions for the exam in botany Biology (1 course)

1. Morphology of plants as a branch of botany. Tasks and directions of development

Morphology of plants, phytomorphology, the science of the patterns of structure and processes of plant formation in their individual and evolutionary-historical development. One of the most important branches of botany. As M.'s development r. plant anatomy, which studies the tissue and cellular structure of their organs, plant embryology, which studies the development of the embryo, and cytology, the science of the structure and development of cells, emerged from it as independent sciences. Thus, M. r. in a narrow sense, it studies the structure and shaping, mainly at the organismic level, however, its competence also includes consideration of the patterns of the population-species level, since it deals with the evolution of form.

Main problems and methods. The main problems of M. R.: the identification of the morphological diversity of plants in nature; studying the regularities of the structure and mutual arrangement of organs and their systems; studies of changes in the general structure and individual organs during the individual development of a plant (ontomorphogenesis); clarification of the origin of plant organs during the evolution of the plant world (phylomorphogenesis); study of the impact of various external and internal factors on shaping. Thus, without being limited to the description of certain types of a structure, M. r. seeks to elucidate the dynamics of structures and their origin. In the form of a plant organism and its parts, the laws of biological organization are externally manifested, that is, the internal interconnections of all processes and structures in the whole organism.

In theoretical M. r. distinguish between 2 interrelated and complementary approaches to the interpretation of morphological data: identifying the causes of the emergence of certain forms (in terms of factors directly affecting morphogenesis) and elucidating the biological significance of these structures for the life of organisms (in terms of fitness), which leads to preservation of certain forms in the process of natural selection.

The main methods of morphological research are descriptive, comparative and experimental. The first is to describe the forms of organs and their systems (organography). The second is in the classification of descriptive material; it is also used in the study of age-related changes in the organism and its organs (comparative ontogenetic method), in elucidating the evolution of organs by comparing them in plants of different systematic groups (comparative phylogenetic method), in studying the influence of the external environment (comparative ecological method). And, finally, with the help of the third - experimental - method, controlled complexes of external conditions are artificially created and the morphological reaction of plants to them is studied, and internal relationships between the organs of a living plant are also studied through surgical intervention.

2. The main vegetative organs of a higher plant, their growth, branching, polarity and symmetry

An organ is a part of a plant that has a certain external (morphological) and internal (anatomical) structure in accordance with its function. There are vegetative and reproductive organs of a plant.

The main vegetative organs of higher plants are the root and shoot (stem with leaves). They provide the processes of nutrition, respiration, conduction of water and substances dissolved in it, as well as vegetative reproduction.

Reproductive organs (spore-bearing spikelets, strobili or cones, flower, fruit, seed) perform functions associated with sexual and asexual reproduction of plants and ensure the existence of the species as a whole, its reproduction and distribution. The dismemberment of the body of plants into organs, the complication of their structure occurred gradually in the process of development of the plant world. The body of the first terrestrial plants - rhinophytes, or psilophytes - was not divided into a root, plant stem and leaves, but was represented by a system of branching axial organs - telomes. As plants emerged onto land and adapted to life in air and soil environments, telomes changed, which led to the formation of organs.

In algae, fungi and lichens, the body is not differentiated into organs, but is represented by a thallus, or thallus of a very diverse appearance.

During the formation of organs, some general patterns are found. With the growth of the plant, the size and weight of the body increase, cells divide and stretch in a certain direction. The first stage of any neoplasm is the orientation of cellular structures in space, i.e. polarity. In higher seed plants, polarity is already found in the zygote and the developing embryo, where two rudimentary organs are formed: a shoot with an apical bud and a root. The movement of many substances occurs along the conductive paths polarly, i.e. in a certain direction.

Another pattern is symmetry. It manifests itself in the location of the side parts in relation to the axis. There are several types of symmetry: radial - two (or more) planes of symmetry can be drawn; bilateral - only one plane of symmetry; at the same time, dorsal (dorsal) and ventral (abdominal) sides are distinguished (for example, leaves, as well as organs growing horizontally, i.e. having plagiotropic growth). Plant shoots growing vertically - orthotropic - have radial symmetry.

In connection with the adaptation of the main organs to new specific conditions, their functions change, which leads to their modifications, or metamorphoses (tubers, bulbs, spines, buds, flowers, etc.). In plant morphology, homologous and similar organs are distinguished. Homologous organs have the same origin, but may differ in form and function. Similar organs perform the same functions and have the same appearance, but are different in their origin.

The organs of higher plants are characterized by oriented growth (movement), which is a reaction to the unilateral action of external factors (light, gravity, humidity). The growth of axial organs towards the light is defined as positive (shoots) and negative (main root) phototropism. The oriented growth of the axial organs of a plant, caused by the unilateral action of the earth's gravity, is defined as geotropism. The positive geotropism of the root causes its directed growth towards the center of the Earth, the negative geotropism of the stem - from the center.

The shoot and root are in their infancy in the embryo in the mature seed. The embryonic shoot consists of an axis (embryonic stalk) and cotyledon leaves, or cotyledons. The number of cotyledons in the embryo of seed plants ranges from 1 to 10-12.

At the end of the axis of the embryo is the growth point of the shoot. It is formed by the meristem and often has a convex surface. This is the cone of growth, or apex. At the top of the shoot (apex), the rudiments of leaves are laid in the form of tubercles or ridges following the cotyledons. Typically, leaf buds grow faster than the stem, with young leaves covering each other and the growing point, forming a bud of the embryo.

The part of the axis where the bases of the cotyledons are located is called the cotyledon node; the rest of the germinal axis, below the cotyledons, is called the hypocotyl, or hypocotyl knee. Its lower end passes into the germinal root, represented so far only by a cone of growth.

When the seed germinates, all the organs of the embryo gradually begin to grow. The germinal root emerges first from the seed. It strengthens the young plant in the soil and begins to absorb water and minerals dissolved in it, giving rise to the main root. The area on the border between the main root and the stem is called the root collar. In most plants, the main root begins to branch, while lateral roots of the second, third and higher orders appear, which leads to the formation of a root system. On the hypocotyl, on old parts of the root, on the stem, and sometimes on the leaves, adventitious roots can form quite early.

3. Root, give definitions. Root functions

Root (lat. radix) is an axial, usually underground vegetative organ of higher plants (vascular plants), which has unlimited growth in length and positive geotropism. The root fixes the plant in the soil and ensures the absorption and conduction of water with dissolved minerals to the stem and leaves.

There are no leaves on the root, and there are no chloroplasts in the root cells.

In addition to the main root, many plants have lateral and adventitious roots. The totality of all the roots of a plant is called the root system. In the case when the main root is slightly expressed, and the adventitious roots are expressed significantly, the root system is called fibrous. If the main root is expressed significantly, the root system is called pivotal.

Some plants lay down reserve nutrients in the root, such formations are called root crops.

Main Functions of the Root

Fixing the plant in the substrate.

Absorption, conduction of water and minerals.

The supply of nutrients in the main root.

Interaction with the roots of other plants (symbiosis), fungi, microorganisms living in the soil (mycorrhiza, nodules of representatives of the legume family).

vegetative reproduction.

Synthesis of biologically active substances.

In many plants, the roots perform special functions (aerial roots, sucker roots).

4. Classification of roots by origin, in relation to the substrate. (Examples)

Classification:

main - develops from the germinal root of the seed, has positive geotropism

adnexal - occur on other plant organs (stem, leaf, flower);

lateral - formed on the main and adventitious roots.

primary root

The first root of a plant, which is laid at the embryo.

In relation to the substrate (habitat) is divided into:

earthen - develop in the soil (in 70% of seed plants);

aquatic - the roots are in the water (in floating aquatic plants);

air - are in the air (in epiphytes - plants that settle on the trunks of other plants);

By form:

cylindrical - the same diameter along the entire length (peony, poppy);

knotty - uneven thickening in the form of knots (meadowsweet)

5. Structure of young root zones

Different parts of the root perform different functions and differ in appearance. These parts are called zones.

The cells of the division zone are thin-walled and filled with cytoplasm; there are no vacuoles. The division zone can be distinguished on a living root by its yellowish color, its length is about 1 mm. Following the division zone is the stretch zone. It is also small in length: it is only a few millimeters, it is distinguished by a light color and, as it were, transparent. The cells of the growth zone no longer divide, but are able to stretch in the longitudinal direction, pushing the root ending deep into the soil. Within the growth zone, cells divide into tissues.

The end of the growth zone is clearly visible by the appearance of numerous root hairs. Root hairs are located in the suction zone, the function of which is clear from its name. Its length is from several millimeters to several centimeters. In contrast to the growth zone, parts of this zone are no longer displaced relative to soil particles. Young roots absorb the bulk of water and nutrients with the help of root hairs.

6. Root systems and their classification. Types of root systems

Root changes:

A root crop is a thickened main root. The main root and the lower part of the stem are involved in the formation of the root crop. Most root plants are biennial. Root crops consist mainly of storage basic tissue (turnips, carrots, parsley).

Root tubers (root cones) are formed as a result of thickening of the lateral and adventitious roots. With their help, the plant blooms faster.

Hook roots are a kind of adventitious roots. With the help of these roots, the plant "sticks" to any support.

Stilted roots - act as a support.

Plank roots are lateral roots that run at or above the soil surface, forming triangular vertical outgrowths adjacent to the trunk. Characteristic of the large trees of the tropical rainforest.

Aerial roots - lateral roots, grow in the aerial part. They absorb rainwater and oxygen from the air. They are formed in many tropical plants in conditions of a lack of mineral salts in the soil of the tropical forest.

Mycorrhiza is the cohabitation of the roots of higher plants with fungal hyphae. With such a mutually beneficial cohabitation, called symbiosis, the plant receives water from the fungus with nutrients dissolved in it, and the fungus receives organic substances. Mycorrhiza is characteristic of the roots of many higher plants, especially woody ones. Fungal hyphae, braiding thick lignified roots of trees and shrubs, act as root hairs.

Bacterial nodules on the roots of higher plants - the cohabitation of higher plants with nitrogen-fixing bacteria - are modified lateral roots adapted to symbiosis with bacteria. Bacteria penetrate the root hairs into young roots and cause them to form nodules. In this symbiotic cohabitation, bacteria convert the nitrogen in the air into a mineral form available to plants. And plants, in turn, provide bacteria with a special habitat in which there is no competition with other types of soil bacteria. Bacteria also use substances found in the roots of higher plants. Most often, bacterial nodules are formed on the roots of plants of the legume family. In connection with this feature, legume seeds are rich in protein, and members of the family are widely used in crop rotation to enrich the soil with nitrogen.

Respiratory roots - in tropical plants - perform the function of additional respiration.

Types of root systems

In the tap root system, the main root is highly developed and clearly visible among other roots (typical for dicots). A variety of tap root system - branched root system: consists of several lateral roots, among which the main root is not distinguished; characteristic of trees.

In the fibrous root system, in the early stages of development, the main root, formed by the germinal root, dies off, and the root system is composed of adventitious roots (typical for monocots). The tap root system usually penetrates deeper into the soil than the fibrous root system, however, the fibrous root system braids adjacent soil particles better.

Adventitious roots grow directly from the stem. They grow from a bulb (which is a special stem) or from garden cuttings.

aerial roots. Roots that grow from the stem but do not penetrate the ground. They are used by climbing plants for anchorage, as in ivy.

Supporting (stilted) roots. A special type of aerial roots. They grow from the stem and then penetrate the ground, which may be covered with water. They support heavy plants such as mangroves.

7. Escape, define. Vegetative and generative shoots, elongated and shortened shoots

Shoot (Latin córmus) is one of the main vegetative organs of higher plants, consisting of a stem with leaves and buds located on it.

Vegetative shoots provide an increase in the total mass and dimensions of the tree and differ in origin and functions performed by them in the crown. From the apical buds, shoots continue to grow from the main or overgrowing branches, they are also called increments, since they annually increase in length and thereby replenish the volume of the tree crown.

If the terminal bud blooms in the year of its formation, a young shoot grows from it, called the summer growth. This growth is very delicate, susceptible to frost and therefore undesirable. One or two kidneys located below the apical,

Generative shoots are the constituent elements of the tree crown, on which the flower buds are laid, and are directly involved in the formation of the crop. These branches got their name due to the fact that only generative buds can be placed on them (even if they do not develop in any year), which determine the propensity of generative branches to bear fruit and their purpose for ensuring the harvest.

Shortened shoots, or brachyblasts - alternate in some plants (grape, vineyard, birch) with elongated ones. This phenomenon is especially pronounced in grape plants. The grape seed gives a small shoot in the first year after germination. From the buds in the axils of its leaves, elongated, well-developed shoots grow the next year, and then, next year, each bud of this shoot gives more frail shoots, which freeze to their lower bud by autumn, so that only one lower one remains from such a shoot. internode. It's called a short run.

The only bud of a short shoot develops in the next growing season powerful elongated shoots, which, in turn, then bring short shoots. Elongated shoots bloom and bear fruit, but short ones do not. In cultivation, due to the short pruning of grapes, this alternation of shortened and elongated shoots is imperceptible, and the plant blooms and bears fruit every year.

8. What organs are part of the shoot, and what functions do they perform? (Escape structure)

Escape structure. Consider a living shoot of some houseplant. You can also take a dried summer shoot of any tree or shrub.

The vegetative shoot consists of a stem, leaves and buds. The buds can be located at the top of the shoot - the apical bud and on its sides above each leaf - the lateral buds. The angle between the leaf and the upper part of the stem is called the leaf axil. Lateral buds are located in the axils of the leaves, and therefore they can be called axillary buds.

The section of the stem from which the leaf and the bud in its axil extends is called the node. The section of the stem between adjacent nodes is an internode. Thus, a vegetative shoot consists of parts that repeat along its length: nodes with leaves and axillary buds and internodes.

Leaf arrangement. Very often, only one leaf departs from the node, as in geranium, tradescantia, oak, linden. This arrangement of leaves on the stem is called regular.

The main function of aboveground vegetative shoots is the creation of organic substances from carbon dioxide and water using solar energy. This process is called air nutrition of plants. We will get to know him in detail later. The main role in this process is played by the leaves of the shoot.

To absorb carbon dioxide, which is contained in the air quite a bit (on average 0.03%), and especially to capture solar energy, a large surface of above-ground organs is needed. This explains the complex structure of the escape. The stem, like a high mast, carries numerous flat leaves into the air - "solar batteries". The more leaves, the larger the illuminated area of ​​the plant. If you add up the area of ​​​​all the leaves, then their total surface will be much larger than the area of ​​\u200b\u200bthe earth's surface occupied by the plant.

9. Classification of shoots according to the nature of their location in space

According to the nature of growth and location in space, the shoots are erect (birch, oak, sunflower, wheat), rising (meadow clover, marsh cinquefoil), creeping (cranberry, highlander bird), creeping (strawberry, goose cinquefoil), climbing (girl's grapes, common ivy), curly (hops, bindweed mountaineer). Clinging plants are attached to the support with the help of tendrils, climbing plants - with sucker roots, and creeping ones - with adventitious roots.

10. Name the main types of shoot branching. Why is the sympodial type considered productive?

SHOT BRANCHING

Occurs during plant growth. There are two main types of branching: dichotomous and monopodial. With dichotomous (forked) branching, two identical branches develop from the growth point. With monopodial branching, the main axis continues to grow, and below its growth point, lateral branches are formed either in ascending sequence or contiguous and forming whorls. Dichotomous branching is usually found in less organized plants - many algae, psilophytes, hepatic mosses, club mosses. Monopodial branching (monopodia) occurs in algae, deciduous mosses, horsetails, seed plants (eg, conifers, maple, beech, many grasses). A false dichotomy can develop from monopodia. Branching is also common, called sympodial. It can develop both from dichotomy and from monopodia and is the result of a faster development of first one of the branches, overtaking the other in its growth, and then overtaking the other branches (the process of “overturning”). As a result, it turns out, as it were, one axis (trunk, stem), but consisting of a number of axes of different orders. Sympodial branching is seen in most woody dicots.

Sympodial branching occurs when the main axis stops growing, but under its apex the lateral bud begins to grow. The shoot that grows out of it outgrows the main axis, shifts it to the side and takes on its direction and appearance. Soon, the apical growth of this shoot also stops, and a new shoot of the third order develops under the growth cone from the lateral bud, etc. Such branching is characteristic of most flowering plants.

A special form of branching is tillering, in which surface and underground side shoots are formed from buds sitting on closely spaced nodes at the base of the shoot. Tillering is characteristic primarily for cereals.

Due to branching, the total mass of the above-ground part of the plant increases, and in woody plants a crown is formed.

11. Stem, define. Stem cross-sectional shapes. The main functions of the stem

Stem - an elongated shoot of higher plants, serving as a mechanical axis, also plays the role of a producing and supporting base for leaves, buds, flowers.

According to the shape of the cross section

rounded

flattened

ribbed

grooved (grooved)

The stem of the plant is the axial part of the shoot, consisting of nodes and internodes. The main role of the stem in the life of the plant is the supporting (mechanical), because the stem contains leaves, buds, flowers, sporulation organs. On the stem, the leaves are optimally arranged in such a way that photosynthesis is carried out with maximum productivity. Also no less important is the function of the plant stem as an intermediary between leaves and roots, that is, conductive. The stem acts as a link between the root system, through which water with minerals enters the plant, and the leaves, where organic substances are synthesized. The conductive tissues of the stem, leaves and roots form a single structure that ensures the movement of substances in the plant body. Thus, the main functions of the stem are supporting and conducting.

Also, the stem can perform a number of other secondary functions, but sometimes they are so hypertrophied that they come to the fore. Thus, the stems of some perennial plants act as a depot of reserve nutrients. The stems of other plants, such as cactus, are covered with thorns, which play a protective role and save the plant from being eaten by animals. And the young stems of plants, in which chlorenchyma is located under the epidermis, actively carry out photosynthesis. This happens in the stalks of asparagus, and the young juicy stalks of asparagus are used as a vegetable for food.

12. Morphology and classification of stem types

The stem is more diverse in external structure than the root. This is primarily due to the diversity of plant habitats. Morphologically, a stem can be defined as a member of a plant that has a radial structure, apical growth and forms leaves and buds in a certain order. The main functions of typical above-ground stems are: providing an increase in the surface of plants through growth and branching; leaf formation and leaf mosaic formation; ensuring communication between roots and leaves; the formation of flowers, through which sexual reproduction of plants takes place. Often, reserve nutrients are deposited in the stems of woody plants and in underground stems.

stem classification

By location relative to soil level

elevated

underground

According to the degree of woodiness

herbaceous

woody (for example, the trunk is the main perennial stem of a tree; the stems of shrubs are called trunks)

According to the direction and nature of growth

upright (e.g. sunflower)

recumbent (creeping) - the stems lie on the surface of the soil without rooting (monetary loosestrife)

ascending (ascending) - the lower part of the stem lies on the surface of the soil, and the upper one rises vertically (cinquefoil)

creeping - the stems spread along the ground and take root due to the formation of adventitious roots at the nodes (ivy-shaped budra)

clinging (climbing) - attached to a support with antennae (peas)

curly - thin stems wrapping around a support (moonseed)

According to the shape of the cross section

rounded

flattened

three-, four-, polyhedral (faceted)

ribbed

grooved (grooved)

winged - stems in which flat grassy outgrowths stretch along sharp edges (forest rank) or bases of leaves flowing down to the stem (comfrey officinalis).

13. Kidneys and their types depending on the structure. Types and functions of kidneys depending on their position on the shoot

The bud of a plant is the beginning of a shoot. In the structure of a plant bud, a rudimentary stem with a growth cone, rudimentary flowers or leaves (depending on the type of bud) are distinguished. Plants have vegetative buds, which consist of leaves located on a rudimentary stem, and generative buds, which carry the rudiments of inflorescences or flowers. If the generative bud has one flower, it is called a bud. Some plants also have vegetative-generative (mixed) buds, which simultaneously have the rudiments of leaves and flowers. The rudiments of the leaves are formed on the cone of growth from the bottom up. Due to the fact that they grow unevenly, they turn up to the top, thereby causing the appearance of a dark and moist enclosed space inside the kidney. This protects the inside of the kidney from drying out and damage. When the bud opens, the bud leaves move away from the primordial stem and straighten due to the growth of the stem internodes.

The buds are gray, brown or brown in color, and on the outside of many woody plants, especially those growing in cold climates, they are covered with dense scales, which are modified leaves that protect the buds from damage and cold. The scales of the kidneys often secrete resinous substances for better protection, as, for example, in poplar, birch. Such kidneys are called protected or closed. If the kidneys do not have scales, they are called bare or unprotected. Additional protection against dehydration and cold is provided by a thick fluff that covers the bare buds of many plants from the outside. In perennial herbaceous plants, for example, lily of the valley, wheatgrass, wintering buds are located on underground shoots or in the lower part of above-ground ones near the ground itself. Due to this arrangement, the kidneys tolerate temperature changes well. In cacti, the kidneys have a special structure and are called areoles, and the kidney scales of such kidneys are converted into needles that perform a protective function.

According to the location on the stem, apical and lateral buds are distinguished. If the formation of a bud occurs at the end of the shoot, then an apical (terminal) bud appears, due to which the shoot grows in length. Thanks to the development of lateral buds, the formation of a system of shoots and their branching is ensured. Lateral buds are called axillary if they are located in the axils of the leaves, and extra-axillary (additional or adnexal) if they are laid in any other part of the stem, including leaves and roots.

In the axils of the leaves, the buds are placed singly or in groups. The distribution of axillary buds on the stem of the plant corresponds to the placement of the leaves, that is, such buds are placed oppositely, alternately, whorled, apically. The location of the buds in the axils of the leaves is of great biological importance, since, in addition to protecting the bud from mechanical damage, large quantities of nutrients come from the green leaf to the bud.

Adnexal buds are not connected either with the tops of the shoots or with the nodes; there is no clear pattern in their location. Thanks to adnexal buds, vegetative propagation is ensured. This is their biological significance. By means of adventitious buds, the reproduction of root plants, for example, sow thistle, aspen, is carried out. Root offspring are shoots that develop from adventitious buds on the roots. Adnexal buds on the leaves of plants develop very rarely. An example is the houseplant Kalanchoe (bryophyllum), whose buds immediately reproduce small shoots with adventitious roots.

The name "renewal buds" refers to those buds of perennial plants that are at rest for a certain period of time due to adverse environmental conditions, and then form shoots when warm, humid weather sets in. So, the kidneys that are at rest in winter are called hibernating, and if there is no winter period in a given climate, then resting. Some kidneys do not have a dormant period. From them, new shoots immediately appear, increasing the surface of the plant.

14. Types of kidneys by origin

The kidney (gemma) consists of: a rudimentary stem with a growth cone, rudimentary leaves (leaf primordia) or flowers, a rudimentary bud. The lower (outer) leaf primordia, due to uneven growth directed upwards and towards the center of the bud, are more or less closed above the inner (upper) primordia, and thus cover them. The scales of the kidneys are often covered with hairs and resinous secretions, which tightly glue the kidney scales and thus also protect the kidneys from freezing and drying out. Such kidneys are called closed. There can be many kidney scales, for example, oak buds have more than 20 of them. Some monocots have a kidney that carries only one kidney scale. Open (naked) kidneys do not have kidney scales. They are typical for aquatic plants, as well as for plants of tropical rainforests, where humidity fluctuations are insignificant.

The buds of various plants are diverse in shape and size.

Types of kidneys by position distinguish between apical and lateral kidneys.

The apical buds ensure the growth of the shoot in length and the formation of new metameres.

Lateral kidneys by origin are divided into axillary and adnexal (adventive).

Axillary buds are located in the axils of the leaves and provide branching of the shoot. The axillary position of the kidneys is of great biological importance. On the one hand, the covering sheet well protects the young kidney from mechanical damage and drying out. On the other hand, the green leaf intensively supplies the kidney with nutrients. In the axils of the leaves, the buds are located either singly or in groups. In the latter case, they can be located one above the other, like honeysuckle, with the lower kidney being the largest. Such kidneys are called serial. In collateral buds, several buds are located in the same plane (onion, bamboo).

15. Morphological diversity of the stem

The morphological diversity of stems is associated with their shape, size, color, presence and feature of pubescence. In woody stems, the nature of the surface, the presence, shape, and number of lentils are added. In herbaceous - position in space.

The shape of the stem in most plants is cylindrical, but it can be trihedral, tetrahedral, polyhedral, ribbed, flattened or flat, winged, barrel-shaped, etc.

The size of the stem in some species is a hereditarily fixed trait, fluctuations of which are possible within the limits of the reaction norm. Eucalyptus trees reach the maximum height for plants - 145-150 m. Of our trees: spruce reaches 50 m in height, pine - 40-50 m, oak - 40 m, birch - 30 m. If we talk about the length of the stem, then the record belongs to tropical climbers ratangam palms, the length of the stems of which reaches 300 m. The thickness of the stems can reach 10-12 m in the baobab and sequoia. The smallest size is characterized by the stem of duckweed, wolfia, bulbophyllum. So, in wolfia it is 1-1.5 mm, in bulbophyllum - 2 mm, in duckweed up to 10 mm.

16. Metamorphosis, give a definition. root metamorphosis

Metamorphosis (from other Greek μεταμόρφωσις - "transformation", in animals it is also called metabolism) - a deep transformation of the structure of the body (or its individual organs) that occurs during individual development (ontogenesis). Metamorphosis in plants and animals differs significantly.

Metamorphosis in plants

It is expressed in the modifications of the main organs that occur in ontogeny and are associated with a change in the functions they perform or the conditions of functioning. True metamorphosis - the transformation of one organ into another with a complete change in form and function, occurs in many herbaceous plants (the gradual death of the above-ground shoot and the transition to a rhizome, bulb, corm during an unfavorable period). In most cases, it is not the differentiated organs of an adult plant that undergo metamorphosis, but their rudiments, for example, when part of the shoots and leaves turn into spines, antennae. The determination of the rudiment of an organ, which determines its final appearance and occurs at different stages of its development, is associated with the accumulation of certain physiologically active substances and depends on external and internal factors.

17. Above-ground modification of shoots, their distinctive features, diversity and biological significance

Modifications of above-ground shoots

An unusual way of life and / or adaptation to the special conditions of the existence of plants lead to various modifications of the shoots. At the same time, shoots can serve not only to store nutrients, reproduce and reproduce plants, but also perform other functions. There are frequent cases when not the entire shoot is modified, but only its leaves, and some of their metamorphoses are outwardly and functionally similar to shoot metamorphoses (thorns, antennae).

Aerial stolons and mustaches - metamorphosis of the shoot, which serves for vegetative reproduction, is a sympodium, consisting of above-ground shoots of vegetative reproduction of an increasing order. Serves to capture the area and resettlement of daughter individuals. For example, a creeping perennial (Ajuga reptans) has a lash, it carries green leaves, participates in photosynthesis, and thus it has not the only reproductive function. But in some plants, such shoots are specialized exclusively for reproduction - they do not carry green leaves, they are thin and fragile, they have very elongated internodes, after rooting their apical bud, they quickly collapse. An example is the whiskers of wild strawberries (Fragaria vesca).

18. Underground modification of shoots, their structure, diversity, biological significance, distinctive features

Modification of underground shoots

Shoots living underground, under the influence of a complex of conditions that are sharply different from the terrestrial environment, almost completely lost the functions of photosynthesis and acquired other equally important vital functions, such as facilitating the transfer of an unfavorable period, storing nutrients, vegetative renewal and plant reproduction. Modified underground shoots include: rhizome, caudex, underground stolon and tuber, bulb, corm.

Rhizome, or rhizome - an underground shoot with scaly leaves of the lower formation, buds and adventitious roots. Thick, highly branched creeping rhizomes are characteristic of couch grass, short and rather fleshy - for kupena, iris, very thick - for capsules, water lilies.

Caudex is a perennial organ of shoot origin of perennial herbs and shrubs with a well-developed taproot that persists throughout the life of the plant. Together with the root, it serves as a place of deposition of reserve substances and bears many renewal buds, some of which may be dormant. There are many caudex plants among the umbrella plants (femur, ferula), legumes (alfalfa, lupins), composites (dandelion, wormwood, rough cornflower).

Underground stolon - an annual elongated thin underground shoot with underdeveloped scaly leaves. At the thickened ends of the stolons, plants can accumulate reserve substances, forming tubers or bulbs (potatoes, stolons, adoxas).

The stem tuber is a modified shoot with a pronounced storage function of the stem, the presence of scaly leaves that quickly peel off, and buds that form in the axils of the leaves and are called eyes (potato, Jerusalem artichoke). Bulb - an underground (rarely above-ground) highly shortened specialized shoot, in which reserve substances are deposited in the scales of a leafy nature, and the stem is transformed into a bottom. The bulb is a typical organ of vegetative renewal and reproduction. Bulbs are characteristic of monocotyledonous plants from the Lily family (lily, tulip, onion), Amaryllis (amaryllis, narcissus, hyacinth), etc. As an exception, they are also found in dicotyledonous plants - in some types of oxalis and butterwort.

A corm is a modified underground shortened shoot with a thick stem that stores assimilants, adventitious roots growing from the underside of the corm, and preserved dried leaf bases (membrane scales), which together form a protective cover. Corms have colchicum, gladiolus, ixia, saffron.

19. List, give a definition. The structure and functions of the sheet

The leaf consists of a base (the place by which it is attached to the stem), a petiole (an elongated narrow part) and a leaf blade (a wide flat part). Some plants, in addition to the leaf, have stipules that are more or less durable. If the leaf petiole is absent, then such a leaf is called sessile.

The value of a leaf for plant life is enormous. The leaves contain a green substance called chlorophyll. In the chlorophyll grains of the leaves, organic substances are created from carbon dioxide, water and mineral salts in the light, from which the plant builds its body. This process is called photosynthesis. It flows only in the light and is accompanied by the release of oxygen.

But leaves not only absorb carbon dioxide and release oxygen. In the process of respiration, they release carbon dioxide and absorb oxygen from the air. During the day, the processes of accumulation of organic substances prevail over respiration, at night - vice versa. Therefore, during the day, plants improve the air in the room, enriching it with oxygen.

The absorption and release of carbon dioxide and oxygen occurs through the smallest holes - stomata, which are often located on the underside of the leaf. Through them, water evaporates, which contributes to the flow of nutrients from the soil through the roots and their promotion through the plant. Evaporation of water also protects plants from overheating. Therefore, it is very important that the leaves are always clean and sufficiently illuminated by sunlight, preferably diffused light.

Many plants have beautiful leaves and are grown indoors for this.

20. Sheet, give a definition. Variety of leaves and leaf formations Leaf (plural leaves, collect. foliage) - in botany, the outer organ of a plant, the main function of which is photosynthesis. For this purpose, the leaf usually has a lamellar structure in order to give the cells containing the specialized pigment chlorophyll in the chloroplasts access to sunlight. The leaf is also the organ of respiration, evaporation and guttation (excretion of water droplets) of the plant. Leaves can retain water and nutrients, and some plants perform other functions.

Main types of leaves

A leaf-like process in certain plant species such as ferns.

Leaves of coniferous trees having a needle-shaped or subulate shape (needles).

Leaves of angiosperms (flowering) plants: the standard form includes stipule, petiole and leaf blade.

Lycopodiophyta (Lycopodiophyta) have microphyllous leaves.

Wrap leaves (a type found in most herbs)

Plant formation (from Latin formatio - education) - a group of plant associations in which the dominant layer is formed by the same species (for example, all associations with a predominance of meadow foxtail or Scots pine). With this understanding of the plant formation, genetically and ecologically different associations can fall into it (for example, in plant formations of pine forests from Scots pine - sphagnum pine forests and pine forests with plants characteristic of broad-leaved forests). On this basis, some modern geobotanists consider it expedient to use the term "Plant formation" as a non-ranking term, not having the meaning of a taxonomic unit. The term plant formation, introduced in 1838 by the German plant geographer A. Grisebach, was used for a long time in a sense close to a plant association or phytocenosis.

21. List, give a definition. Forms of leaf blades, the main types of vein coriation of leaves of angiosperms

Leaf (plural leaves, collect. foliage) - in botany, the outer organ of a plant, the main function of which is photosynthesis. For this purpose, the leaf usually has a lamellar structure in order to give the cells containing the specialized pigment chlorophyll in the chloroplasts access to sunlight. The leaf is also the organ of respiration, evaporation and guttation (excretion of water droplets) of the plant. Leaves can retain water and nutrients, and some plants perform other functions.

The main forms of the leaf blade

1. Broadly ovate leaf

2. Rounded

3. Reverse broad ovoid

4. Ovate

5. Elliptical

6. Obovate

7. Narrow ovoid

8. Lancet

9. Oblong

10. Reverse narrow ovoid

11. Linear

Leaf veins are vascular tissue and are located in the spongy layer of the mesophyll. According to the branching pattern of the vein, as a rule, they repeat the branching structure of the plant. The veins consist of xylem - a tissue that serves to conduct water and minerals dissolved in it, and phloem - a tissue that serves to conduct organic substances synthesized by leaves. The xylem usually lies on top of the phloem. Together they form the underlying tissue called the leaf pith.

An angiosperm leaf consists of a petiole (leaf stalk), leaf blade (blade) and stipules (paired appendages located on both sides of the petiole base). The place where the petiole meets the stem is called the leaf sheath. The angle formed by the leaf (leaf petiole) and the superior internode of the stem is called the leaf axil. A bud (which in this case is called an axillary bud), a flower (called an axillary flower), an inflorescence (called an axillary inflorescence) can form in the leaf axil.

22. General characteristics and distinctive features of the sheet. The emergence of the leaf in the process of revolution

The leaf in the evolution of plants arose 2 times. In the Devonian, an enation leaf arose, also called phylloids and microphylls. It appeared as a scaly outgrowth on the shoot, which served to increase the area of ​​the photosynthetic surface. This outgrowth had to be supplied with water and the products of photosynthesis had to be taken from it, so the conducting system penetrated into it. Now such leaves are characteristic of lycopsform and psilotoid. The leaf trace of the microphylla is attached to the stele without the formation of leaf lacunae. It is laid down in the apical meristem. For the second time, a telome leaf or macrophyll arose. It arose on the basis of a group of telomes located in the same plane, which flattened and fused. This type of leaf is typical for horsetails, ferns, gymnosperms and flowering plants. There is also a point of view that enations are a reduction of macrophylls.

23. Parts of the sheet and their functions. The leaves are simple and compound. Edge character, general shape

The most important and noticeable part of typical leaves is the so-called leaf blade, the largest part of it, which is usually what they mean when talking about a leaf. In many plants, between the leaf blade and the stem, there is a petiole, similar in appearance to the stem, but in origin being part of the leaf. Petioles serve to better position the leaves on the stem in relation to the light. Leaves with petioles are called petiolate, and those without petioles are called sessile. In many plants, the lower part of the leaf is widened, grooved, and often more or less encircles the stem in the form of a tube; it is called the vagina and is characteristic of cereals, sedges, many umbrella, orchid, etc. The vagina protects the axillary buds and young, long-growing bases of internodes (in cereals); sometimes it probably increases the bending strength of the stem. In some plants, such as bananas, leaf sheaths, embracing each other, form a false high stem. In many plants, the lower leaves, and in some, all are reduced to sheaths alone.

In its form, the sheet can be:

Fan-shaped: semi-circular, or in the form of a fan

Bipinnate: Each leaf is pinnate

Deltoid: leaf is triangular, attached to the stem at the base of the triangle

Lateform: Divided into many lobes

Pointed: wedge-shaped with a long apex

Needle: thin and sharp

Cuneiform: the leaf is triangular, the leaf is attached to the stem at the apex

Spear-shaped: sharp, with spines

Lanceolate: the leaf is long, wide in the middle

Linear: the leaf is long and very narrow

Bladed: with multiple blades

Spatulate: spade-shaped leaf

Unpaired: pinnate leaf with apical leaflet

Oblanceolate: upper part is wider than the lower part

The edge of the leaf is often a characteristic of the plant genus and helps to identify the species:

Whole-edged - with a smooth edge, without teeth

Ciliated - fringed around the edges

Toothed - with teeth, like a chestnut. The step of the clove can be large and small.

Round-toothed - with wavy teeth, like a beech.

finely serrated - finely serrated

Lobed - indented, with notches that do not reach the middle, like many oaks

Serrated - with asymmetrical teeth directed forward towards the top of the leaf, like a nettle.

Two-toothed - each clove has smaller teeth

Finely serrated - with small asymmetrical teeth

Notched - with deep, wavy cuts, like many species of sorrel

Spiny - with inelastic, sharp ends, like some hollies and thistles.

24. Morphology of the plates of simple leaves or compound leaves, the nature of the edge, the general shape

The most essential part of a leaf is its lamina, which varies greatly in shape, size, texture, etc., in different plants. The characteristic of the leaf blade occupies a fairly prominent place in the scientific description (diagnosis)1 of a plant, and an extensive terminology has been developed for it; already Linnaeus (1707-1778) counted 170 different types of leaves.

Leaf blades are described by their general shape, by consistency, by the outline (contours) of the entire blade, its base and top, by dissection, pubescence, the nature of the surface, venation, etc. (Fig. 222).

According to the dissection of the leaf blade, there are a number of transitions from completely entire leaves to strongly dissected and, finally, complex, in which the blade is divided into several leaflets, attached to the common petiole mostly through independent petioles or special joints.

The veins, or, as they are often unfortunately called, "nerves", passing through the leaf, are vascular bundles, which then go to the stem. The vast majority of them, except for the thinnest, along with the cells of wood and bast, also contain sclerenchymal fibers. The functions of the veins are: conductive - delivery of water and mineral salts to the leaf, removal of the produced assimilates from it - and mechanical - support for the leaf parenchyma and protection of the leaves from ruptures.

25. Morphology of the blades of simple leaves or leaflets of compound leaves

From the way the leaf blades are divided, two main leaf shapes can be described.

A simple leaf consists of a single leaf blade and one petiole. Although it may be composed of several lobes, the spaces between these lobes do not reach the main leaf vein. A simple leaf always falls entirely. If the recesses along the edge of a simple sheet do not reach a quarter of the half-width of the sheet plate, then such a simple sheet is called solid. A compound leaf consists of several leaflets located on a common petiole (called a rachis). Leaflets, in addition to their leaf blade, may also have their own petiole (which is called petiole, or secondary petiole). In a complex sheet, each plate falls off separately. Since each leaflet of a compound leaf can be considered as a separate leaf, it is very important to locate the petiole when identifying a plant. Compound leaves are characteristic of some higher plants such as legumes.

The leaves of a simple form consist of one leaf plate, attached to one petiole. They have solid edges or cut in the form of teeth, notches, notches (small or large, sharp, blunt, uniform or heterogeneous). The simplest forms have leaves with solid leaf plates:

The linear form of the leaf (Fig. 4) is most characteristic of herbaceous plants of the family of cereals, sedges, rushes, irises. The leaf of this form is long and narrow, the venation is usually linear, unbranched, longitudinal. There are forms more or less wide (broad-linear and narrow-linear), more often with solid edges or slightly ribbed or serrated.

26. Leaf arrangement and its variants. The main patterns of leaf arrangement. Leaf mosaic

Leaf arrangement is the arrangement of leaves on the stem, reflecting the symmetry in the structure of the shoot. L. depends primarily on the order of initiation of leaf primordia on the cone of growth and is usually a systematic feature. There are 3 main types of L.: spiral, or next, - 1 leaf departs from each node of the stem (oak, birch, cereals, umbrella); opposite - on each node 2 leaves sit opposite each other (maple, lilac, labiales); whorled - each node carries 3 or more leaves (oleander, elodea, urut). The general pattern of all types of L. is an equal angular distance between leaves sitting on the same node or on successive nodes of the spiral, called the main genetic spiral (see Fig.). For opposite and whorled L., the alternation of leaves of adjacent pairs or whorls is characteristic; at the same time, vertical rows of leaves (ortostichs) are formed on the stem, in a number twice as large as the number of leaves on one node. Spiral L. in terms of the number of orthosties and the magnitude of the angles of divergence (divergence) between successive leaves can be varied and is expressed by the L. formula, which is a fraction corresponding to the value of the angle of divergence in fractions of a circle. The most common are 1/2 (double-row L.), 1/3 (three-row L.), 2/5, less often - 3/8, 5/13, etc. The denominator of the fraction shows the number of orthostiches; the larger it is, the less the leaves shade each other. The reasons for the correctness of L. are associated with the size of the growth cone and leaf primordia and their mutual influence. According to one of the hypotheses, each leaf rudiment forms around itself a physiological field that inhibits the initiation of new primordia in close proximity to it, according to another, the initiation of each subsequent leaf rudiment is not inhibited, but stimulated by the previous one.

Leaf mosaic - the arrangement of the leaves of plants in the same plane, usually perpendicular to the direction of the rays of light, which ensures the least shading of each other's leaves.

27. Leaf lifespan. Evergreen and deciduous plants. Biochemical and morphological preparation of plants and its biological significance

The life span of green leaves developed on shoots varies from plant species to 2-3 weeks to 20 years or more. In general, it should be noted that the leaves of perennial plants, compared with the stem and root, have the shortest life span. This is apparently due to the fact that the leaf tissues, having formed, are no longer renewed, and on the other hand, the leaves function very actively during their relatively short life.

There are deciduous and evergreen plant species. The former are characterized by the fact that annually for a certain period they are in a leafless state, and this period usually coincides with unfavorable environmental conditions. For example, most of our trees and shrubs do not have leaves in winter.

Evergreens are characterized by having green leaves throughout the year. But this does not mean that their leaf is preserved and functions forever, throughout the life of the individual. Evergreens also have leaf fall, but older leaves fall from the plant and the leaves that formed at a later date are always preserved.

Tropical rainforests are characterized by evergreens, although there are also plants with leaves that last less than a year. But during this period of time, the buds repeatedly open and give rise to new leafy shoots. In tropical forests, plants with leaves that live for several years are also common. There are plants that, although for a short period of time in the year, may be in a leafless state.

Leaf fall is a biological process, due to the development of the plant organism and its vital activity. Leaf fall is preceded by leaf aging: the intensity of vital processes occurring in its cells (photosynthesis, respiration) decreases, the content of ribonucleic acid, nitrogen and potassium compounds decreases. Hydrolysis prevails over the synthesis of substances; end products of decay accumulate in cells (for example, calcium oxalate crystals). The most valuable mineral and plastic compounds leave the leaves. Their outflow usually coincides either with the formation and growth of new organs, or with the deposition of reserve substances in ready-made storage tissues. In experiments, it was possible to extend the life of the leaves by removing buds or other formations on the plant, where plastic and mineral substances from the leaves can enter. The transfer of substances to places of their reuse is considered as one of the causes of aging and leaf fall.

28. The structure of the plant seed. Morphological types of seeds

The seed develops on the surface of the seed scale. It is a multicellular structure that combines storage tissue - endosperm, embryo and a special protective cover (seed peel). Before fertilization, the central part of the ovule contains the nucellus, which is gradually replaced by the endosperm. The endosperm is haploid and is formed from the tissues of the female gametophyte.

In cycads and ginkgoes, the outer layer of the seed coat (sarcotesta) is soft and fleshy, the middle layer (sclerotesta) is hard, and the inner layer (endotesta) is membranous by the time the seed ripens. The seeds are dispersed by various animals that eat the sarcotesta without damaging the sclerotesta.

In yew and podocarpus, the seeds are surrounded by a fleshy aryllus, a highly modified scale of the female cone. The juicy and brightly colored arillus attracts birds that spread the seeds of these conifers. Arillus of many species of podocarpus are also edible for humans.

Seeds in seed plants are formed from the ovule.

Seeds of gymnosperms have a dense seed coat, sometimes provided with a pterygoid outgrowth. Under the seed coat is a membranous structure - the remainder of the nucellus. The rest of the seed volume is occupied by the overgrown body of the gametophyte, transformed into a nutrient tissue, and the embryo. The embryo is located in a special chamber. The embryo consists of a root, a stalk, cotyledons and a kidney. The embryo is connected with the nourishing tissue by a pendant that extends from the embryonic root.

Seeds of angiosperms vary greatly in weight, size, color, and surface pattern.

29. Conditions necessary for seed germination. Seed dormancy and its biological significance

seed germination conditions

Temperature

Plant seeds germinate at a positive temperature. The temperature at which germination begins varies widely among plants of different taxonomic groups and geographic regions. On average, seeds of plants of polar and temperate latitudes germinate at a lower temperature than seeds of subtropical and tropical species. The optimal germination temperature is also different, at which the greatest germination and maximum germination are observed.

Seeds of some plants withstand periods of short-term exposure to high temperatures during forest fires, after which favorable conditions are created for the germination of surviving seeds. In addition, fire contributes to the opening of the fruits of some plant species that are resistant to fire. So, only after the fires are the “late” cones of the lodgepole pine, the cones of the sequoiadendron, etc., the fruits of some species of the genus Banksia, opened.

Oxygen

Stratification

Scarification

Scarification - damage by mechanical or chemical action of the seed coat, necessary for their germination. It is usually required for seeds with a thick and strong seed coat (many legumes) or endocarp (for example, raspberries, bird cherry).

In nature, exposure to bacteria and soil humic acids, as well as passage through the gastrointestinal tract of various animals, can serve as a scarifying agent.

It is assumed that the seeds of some plants (for example, calvaria Sideroxylon grandiflorum) cannot germinate in nature without passing through the intestines of birds. So, the seeds of calvaria could be germinated only after they passed through the intestines of domestic turkeys or were treated with polishing paste.

Some seeds require both scarification and stratification at the same time. And sometimes (hawthorn) most of the seeds germinate after scarification and double stratification, that is, after two winter dormant periods.

Resting state

Seed germination

Seed germination is their ability to give normal seedlings (in the laboratory) or seedlings (in the field) for a certain period of time. Germination strongly depends on the conditions of germination and storage conditions of seeds. Germination is usually expressed as a percentage (this is the percentage of seeds that germinated out of the total number of seeds).

With long-term storage of seeds, their germination decreases over time. The seeds of some plants lose their viability after 2-3 weeks (for example, the seeds of most willow species completely lose their viability at a temperature of 18-20 ° C for a month). The germination of seeds of most cultivated plants noticeably decreases after 2-3 years. Lotus seeds in peat remain viable for at least 250 years (according to some sources, more than a thousand years). The seeds of Arctic lupine preserved in the permafrost managed to germinate after 10-12 thousand years.

30. Variety of leaves within one plant. Layered categories of leaves. Heterophilia

Diversity - the property of plants to change the shape of leaves within one individual plant (both along the length of the shoot, and in two different habitats). The change in the shape of the leaves within the same shoot is caused by differences between the functions they perform. Plants often have three leaf formations: bottom, middle, and top. So, in a woody plant, linden buds are covered with scaly brown leaves, then heart-shaped green leaves typical of the species and bracts develop - a completely different shape, lanceolate, light green in color. The same phenomenon is observed in herbs. So, in onions, dry and juicy bulb scales are grassroots leaves, green tubular ones are middle ones, and membranous colorless bracts surrounding the inflorescence are apical. Some plants that live in the aquatic environment may also have leaves of various shapes. So, in the arrowhead, the underwater leaves are linear, the above-water ones are arrow-shaped, and in the water buttercup, the underwater leaves are multi-digitally dissected, and the above-water ones are oval. This phenomenon is called heterophylly. It is associated with adaptation to different pressures of environmental factors - in water, the surface area of ​​the leaves should be as small as possible - this reduces resistance, and in the air, where photosynthesis is actively taking place, the area should be as large as possible.

Heterophilia is the presence of leaves of different structures on the same plant. A good example is the common arrowhead (Sagittatia sagittifiolia), which has different above- and underwater leaves. In general, this phenomenon is inherent in aquatic plants.

Riding - develop in the area of ​​\u200b\u200bthe inflorescence, these are bracts. They are underdeveloped, with a slightly dissected leaf blade, green (may attract pollinators and be brightly colored in this case);

Median - develop in the middle part of the shoot. They are green (perform the function of assimilation), have the largest size, the leaf blade is characterized by the greatest degree of dissection;

Grassroots - develop at the bottom of the shoot. They are white at first, then turn brown as the leaves age, and turn black when they die. They perform the function of protection or storage, or both.

31. Modifications of leaves or parts of leaves, their structure and biological significance. Examples of apalogous and homologous organs in plants

Leaf modifications

Some plants change (and often quite significantly) the structure of the leaves for one purpose or another. Modified leaves can perform the functions of protection, storage of substances, and others. The following metamorphoses are known:

Leaf spines - may be derivatives of the leaf blade - lignified veins (barberry), or stipules (acacia) can turn into spines. Such formations perform a protective function. Spines can also be formed from shoots (see Modifications of stems). Differences: spines formed from shoots grow from the axils of the leaf.

Antennae are formed from the upper parts of the leaves. They perform a supporting function, clinging to surrounding objects (example: China, peas).

Phyllodes are petioles that take on a leaf-like shape and carry out photosynthesis. In this case, the true leaves are reduced.

Trapping leaves are modified leaves that serve as trapping organs of carnivorous plants. Catching mechanisms can be different: droplets of sticky secretion on the leaves (dew), vesicles with valves (pemphigus), etc.

Saccular leaves are formed due to the fusion of the edges of the leaf along the midrib, so that a bag with a hole at the top is obtained. The former upper sides of the leaves become inner in the bag. The resulting container is used to store water. Through the holes, adventitious roots grow inward, absorbing this water. Sack-shaped leaves are characteristic of the tropical liana Raffles dyschidia

Succulent leaves - leaves that serve to store water (Aloe, agave).

Similar organs (in plants)

The morphology of plants presents many examples of similar organs, i.e., such formations, the origin of which is different, but the functions are the same. So, the roots are similar to rhizoids, the spines are thorns, the seeds are spores. The similarity of functions often causes a great similarity of the external form. So, in the case of underdevelopment of leaves, the stems, which take over the work of assimilation, usually become flat and wide, acquiring a resemblance to leaves. Particularly interesting are the assimilating stems (cladodia or phylocladia) in Ruscus species. Here, the cladodia are so similar to leaves that for a long time there were disputes whether they were leaves or stems. In the same way, tubers are similar, whether they come from stems or roots, thorns and tendrils are similar, whether they come from leaves or from whole branches.

Homologous organs (Greek "homos" - the same) - organs that are similar in origin, structure, but perform different functions. Their appearance is the result of divergence. An example of homologous organs in animals is the forelimbs, consisting of the same bones, having the same origin, but performing different functions: in amphibians, reptiles, in most animals they serve for walking, in birds - for flying, in whales - for swimming, in mole - for digging the earth, a person performs the finest operations in the labor process. In plants, the homologous organs are the fern growth, the primary endosperm of the pine ovule, and the embryo sac of the flowering plant. All of them are formed from spores, have a haploid set of chromosomes and carry a female gamete - an egg. But the fern growth is an autotrophic plant with archegonia. The primary endosperm of the pine is part of the ovule, and then the seed as a storage tissue. The formed embryo sac has eight cells, and only three of them take part in the development of the seed, the rest die off. Homologous organs indicate that in the course of adaptive evolution, traits undergo profound changes that lead to the formation of new species, genera, and larger systematic groups of animals and plants.

32. General ideas about the reproduction of higher plants. Comparative characteristics of different types of reproduction, their biological significance for higher plants

vegetative reproduction. Vegetative propagation is an increase in the number of independent individuals due to the separation from the mother plant of its non-specialized or specialized parts capable of independent existence and development. The ability to vegetative reproduction is inherent in many plants. It is possessed by more than 90% of the species of herbaceous plants in the broad-leaved forests of Europe (Fedorov et al., 1962). Vegetative reproduction is especially widespread in plants growing under conditions favorable for seed reproduction, such as a short growing season, strong shading, excessive moisture, lack of pollinators, etc. Due to its wide distribution in nature, vegetative propagation plays an important role in maintaining the population of a particular species. According to R.E. Levina (1964), the ability for abundant vegetative reproduction is of great adaptive importance and often ensures the dominant position of the species in the phytocenosis. Compared with sexual reproduction, vegetative reproduction has a number of advantages. It is simple, reliable, and, moreover, often ensures the rapid dispersal of the species in the territory (Daddington, 1972). The survival of vegetative progeny in the same species is higher than the survival of seed progeny (Cenopopulations of Plants, 1988).

Asexual reproduction is what happens with the help of specialized cells - spores. Unlike gametes, spores directly, i.e. without fusion with other cells, germinate into a new plant.

In lower plants, spores are often equipped with flagella. They are called zoospores. If the spores of lower plants lack flagella, they are called aplanospores. In higher plants, spores never have flagella.

Spores are formed in special receptacles - sporangia. In lower plants, sporangia are unicellular, in higher plants they are multicellular. Inside the sporangium, sporogenous tissue is formed. The cells of this tissue divide by mitosis or meiosis and form spores.

By origin, spores are divided into mitospores and meiospores. Mitospores are formed as a result of mitotic division. They grow into adults. There is a similar type of spores in some lower plants. Meiospores are formed as a result of reduction division. Germinating, they develop into haploid formations - gametophytes. A similar type of spores is characteristic of all higher and some lower plants. This is the most advanced way of reproduction. It consists in the fusion of two specialized cells - gametes, and the formation of a zygote, from which a new individual develops. During sexual reproduction, the hereditary characteristics of two organisms (maternal and paternal) are combined. As a result, the resulting offspring are more genetically diverse, which contributes to a more successful survival of the species.

33. Methods of natural and artificial vegetative propagation of plants. The economic importance of vegetative propagation of plants

Natural vegetative propagation

Vegetative propagation of plants is based on their widespread ability to regenerate, that is, to restore lost organs or parts, or in general to develop the whole plant again from individual parts of the body. In animals, the ability to regenerate is the higher, the lower the animal is in the system.

Among plants of the lower groups, the ability to regenerate is also great, for example, in many mosses, almost all the cells of the body of their body are potentially capable of developing a new plant. Moreover, in more rare cases, renewal occurs directly at the site of injury; more often, somewhere near the wound, a neoplasm occurs or the wound causes the growth of organs already laid down, but which were in their infancy.

In unicellular plants, their reproduction by cell division can be considered vegetative reproduction.

Artificial vegetative propagation

A sharp boundary cannot be drawn between natural and artificial vegetative reproduction.

It can conditionally be called artificial reproduction, which does not take place in nature, since it is associated with the surgical separation from the plant of its parts used for reproduction. Propagation of cultivated plants by tubers or baby bulbs separated from the mother plant occupies an intermediate position between natural and artificial vegetative propagation. Artificial vegetative propagation is resorted to if the plant does not produce seeds under the given conditions of culture, or produces few seeds, of poor quality, if the properties of the variety are not preserved during propagation by seeds, which is usually the case with hybrids, or if it is necessary to quickly propagate this plant or this variety.

IV Michurin attached great importance to vegetative propagation of plants. He believed that from any plant, by prolonged exposure to it, it is possible to obtain offspring that are easily propagated by cuttings.

34. General characteristics of a flower. Organs and parts of a flower, their functions and formation in the process of flower ontogenesis

A flower is an organ, or rather, a whole system of organs, characteristic of the order of flowering, or angiosperms (magnoliophyta, or angiospermae). The main functions of a flower are to promote pollination and fertilization, the formation and development of the fetus, in other words, reproduction. The shapes, sizes, colors of flowers are extremely diverse, but they all have characteristic structural elements.

A flower consists of a stem part (pedicel and receptacle), a leaf part (sepals, petals) and a generative part (stamens, pistil or pistils). The flower occupies an apical position, but at the same time it can be located both on the top of the main shoot and on the side. It is attached to the stem by means of a pedicel. If the pedicel is greatly shortened or absent, the flower is called sessile (plantain, verbena, clover).

On the pedicel there are also two (in dicotyledonous) and one (in monocotyledonous) small preleaves - bracts, which may often be absent. The upper expanded part of the pedicel is called the receptacle, on which all the organs of the flower are located. The receptacle can have different sizes and shapes - flat (peony), convex (strawberry, raspberry), concave (almond), elongated (magnolia). In some plants, as a result of the fusion of the receptacle, the lower parts of the integument and the androecium, a special structure is formed - hypanthium. The form of hypanthium can be varied and sometimes participate in the formation of the fetus (cynarrhodia - rosehip, apple). Hypanthium is typical for representatives of the rose, gooseberry, saxifrage, and legume families.

Parts of a flower are divided into fertile, or reproductive (stamens, pistil or pistils), and sterile (perianth).

35. Gender of a flower. Monoecious and dioecious plants. asexual flowers

Depending on the sex, the flower is: asexual, if only integuments are present in it, and the gynoecium and androecium do not develop (marginal flowers of blue cornflower); bisexual, if it contains both androecium and gynoecium (pea, apple tree); unisexual if it contains only the androecium or only the gynoecium. Among the latter, staminate flowers (common oak) and pistillate (common oak, Babylon willow) are distinguished.

Plants in which same-sex flowers are located separately (in corn: male - in a panicle at the top of the plant, female - in the inflorescence-cob), but on the same plant, are called monoecious (birch, hazel, oak, beech, alder, many sedges, pumpkin ). Plants in which same-sex (male and female) flowers are located on different plants are called dioecious (hemp, sorrel, spinach, willow, aspen, etc.).

Monoecious plants are about 5-8%, dioecious are somewhat less - 3-4%.

There are species in which bisexual and unisexual flowers can be found on the same plant. These are the so-called polygamous (polygamous) plants (buckwheat, ash, many types of maple, melon, sunflower, dahlias, horse chestnut).

Flower male (contains only stamens);

Flower female (contains only carpels);

The flower is bisexual.

36. Flower, define. Classification of flowers according to symmetry features

A flower (plural flowers, lat. flos -oris, Greek ἄνθος -ου) is a complex organ of seed reproduction of flowering (angiosperms) plants.

The flower is a modified, shortened and limited in growth spore-bearing shoot, adapted for the formation of spores, gametes, as well as for the sexual process, culminating in the formation of a fruit with seeds. The exclusive role of a flower as a special morphological structure is due to the fact that it completely combines all the processes of asexual and sexual reproduction. The flower differs from the cone of gymnosperms in that, as a result of pollination, pollen falls on the stigma of the pistil, and not directly on the ovule, and during the subsequent sexual process, the ovules in flowering plants develop into seeds inside the ovary.

One of the characteristic features of the structure of a flower is its symmetry. According to the symmetry features, the flowers are divided into actinomorphic, or regular, through which several planes of symmetry can be drawn, each of which divides it into two equal parts (umbrella, cabbage), and zygomorphic, or irregular, through which only one vertical plane of symmetry can be drawn. (legumes, cereals).

If not a single plane of symmetry can be drawn through a flower, it is called asymmetrical, or asymmetrical (valerian officinalis, canna).

By analogy with actinomorphism, zygomorphism and asymmetry of the flower as a whole, they also speak of actinomorphism, zygomorphism and asymmetry of the corolla.

For a brief and conventional designation of the structure of flowers, formulas are used in which, using alphabetic and numerical designations, various morphological features are encoded: the sex and symmetry of the flower, the number of circles in the flower, as well as the number of members in each circle, the fusion of parts of the flower and the position of the pistils (upper or lower ovary).

The most complete picture of the structure of a flower is given by diagrams that represent a schematic projection of a flower onto a plane perpendicular to the axis of the flower and passing through the covering leaf and the axis of the inflorescence or shoot on which the flower is located.

37. Perianth and its types. Morphology of the calyx and its corolla. Their origin in the process of revolution

The perianth is the sterile part of the flower that protects the more delicate stamens and pistils. Perianth elements are called tepals, or perianth segments. In a simple perianth, all leaflets are the same; in the double, they are differentiated. The green tepals of a double perianth form a calyx and are called sepals, the colored tepals of a double perianth form a corolla and are called petals. In the vast majority of plants, the perianth is double (cherry, bluebell, carnation). A simple perianth can be cup-shaped (sorrel, beetroot) or (more often) corolla-shaped (goose onion). In a small number of species, the flower is generally devoid of perianth and is therefore called uncovered, or naked (cala, willow).

The flower of one of the buttercups - larkspur, with five blue sepals and a white eye formed by nectary petals and staminode petals

The calyx consists of sepals and forms the outer circle of the perianth. The main function of the sepals is to protect the developing parts of the flower before it blooms. Sometimes the corolla is completely absent, or greatly reduced, and the sepals take on a petal-like shape and are brightly colored (for example, in some buttercups). Sepals can be isolated from each other or grow together.

The corolla (lat. corolla) is formed by a different number of petals and forms a circle following the calyx in the flower. The origin of the petals may be related to vegetative leaves, but in most species they are thickened and overgrown sterile stamens. Near the base of the petals, additional structures are sometimes formed, which are collectively called the corolla. Like the sepals, the petals of the corolla can fuse with themselves at the edges (corolla corolla) or remain free (free-petal, or separate-petal corolla). A special specialized type of corolla, the moth-type corolla, is observed in plants from the subfamily Moths of the legume family.

38. Androceum. The structure of the stamen, its origin and evolution. Androecium types

The stamen is the male reproductive organ of an angiosperm flower. The totality of stamens is called androecium (from ancient Greek ἀνήρ, genitive ἀνδρός - “man” and οἰκία - “dwelling”).

Most botanists believe that stamens are modified microsporophylls of some extinct gymnosperms.

The number of stamens in one flower in different angiosperms varies widely from one (orchid) to several hundred (mimosa). As a rule, the number of stamens is constant for a certain species. Often, stamens located in the same flower have a different structure (according to the shape or length of the stamen filaments).

The stamens may be free or fused. According to the number of groups of fused stamens, different types of androecium are distinguished: unifraternal, if the stamens grow together into one group (lupine, camellia); bifraternal, if the stamens grow together in two groups; polyfraternal, if numerous stamens fuse into several groups; fraternal - the stamens remain unfused.

The stamen consists of a filament, by means of which it is attached to the receptacle with its lower end, and an anther at its upper end. The anther has two halves (theca), now connected by a connective, which is a continuation of the stamen filament. Each half is divided into two nests - two microsporangia. Anther nests are sometimes called pollen sacs. Outside, the anther is covered with an epidermis with a cuticle and stomata, then a layer of endothecium is located, due to which the nests open when the anther dries. Deeper in the young anther is the middle layer. The content of the cells of the innermost layer - the tapetum - serves as food for the developing mother cells of microspores (microsporocytes). In the mature anther, the partitions between the nests are most often absent, the tapetum and the middle layer disappear.

Two important processes take place in the anther: microsporogenesis and microgametogenesis. In some plants (flax, stork), part of the stamens becomes sterile. Such barren stamens are called staminodes. Often the stamens function as nectaries (blueberries, blueberries, cloves).

ANDROCEUM, the male part of a flower. Contains stamens; each consists of a bilobed anther containing pollen on a thin stalk called a filament.

Androecium types.

1 - four-strong (in cruciferous), 2 - two-strong (characteristic of many labiales), 3 - bifraternal (bean subfamilies of moths), 4 - androecium with anthers glued into a tube (composites).

39. Gynoecium. The structure of the pistil. Origin of the gynoecium. Types of ovaries and their evolution.

Gynoecium (lat. gynaeceum) - a set of carpels of a flower.

Other definition of gynoecium is the collection of pistils in a flower (that is, the collection of flower parts formed by carpels).

In full flowers, such as lilies, levkoy, peony, etc., it occupies the central part of the flower. It consists of one or more parts, called carpels or carpels (the term pistil is also used in the literature, which many botanists consider redundant), from which fruits are subsequently formed.

If there is one carpel in the gynoecium, the gynoecium is called monomerous, if there are many, it is called polynomial.

The carpels, growing together at the edges, form a pistil, which in a typical case consists of three parts:

lower swollen - ovary (lat. germen);

column (lat. stylus), which is a direct continuation of the ovary;

stigma (lat. stygma), ending with a column.

The ovary contains one or more ovules (ovules). These are very small, sometimes barely noticeable bodies that undergo fertilization and then turn into seeds.

The column, which in many plants is not developed at all or is very poorly developed, contains a channel inside itself, lined with a delicate and loose tissue, often completely filling it. Through it, fertilization occurs.

The stigma is lined, like the channel of the style, with the same loose tissue, which seeps out of itself thick sugary moisture and receives fruitful dust.

In a polynomial gynoecium, the pistils may be free or grow together. In the first case, the polynomiality of the gynoecium is quite clear, in the second, the fusion is different. Sometimes only the ovaries grow together, and then there are as many columns as there are pistils in the gynoecium, and sometimes the fusion concerns both the ovaries and the columns. In the second case, the gynoecium appears to be whole, consisting, as it were, of one pistil; the number of pistils can be determined either by the number of stigmas, or at least by the number of stigma lobes.

Ovary - a term of plant morphology; closed hollow receptacle, the lower swollen part of the pistil of a bisexual or female flower. The ovary contains well-protected ovules. After fertilization, the ovary turns into a fruit, inside which are the seeds developed from the ovules.

The ovary acts as a moist chamber that protects the ovules from drying out, fluctuations in temperature and eating them by insects.

The ovary and stigma of the pistil, which serves to trap pollen, are connected by a column (if there are several pistils in the flower, their upper narrowed parts are called stylodies).

The ovary can be single- or multi-celled (in the latter case, it is divided by septa into nests; sometimes the nests are separated by false septa).

According to the type of arrangement in the flower, the ovaries are called:

The upper (free) ovary is attached by the base to the receptacle, without growing together with any parts of the flower (in this case, the flower is called sub-pest or near-pest).

The lower ovary is located under the receptacle, the remaining parts of the flower are attached at its top (in this case, the flower is called supraspinal).

40. Types of gynoecium and their evolution

In the process of evolution of the gynoecium, the carpels gradually coalesce with each other and from the apocarpous gynoecium a cenocarpous one (from the Greek kainos - common) arises. In the cenocarpous gynoecium, individual columns (stylodia) can remain free or grow together, forming one common column (complex column). There are three types of coenocarpous gynoecium: syncarpous, paracarpous, and lysicarpous.

Syncarpous (from Greek syn - together) is called a gynoecium from a different number of closed carpels, fused together by lateral parts. It is two-multi-celled and is characterized by the fact that the ovules are located along the seams of closed carpels, i.e. at the corners formed by their abdominal parts (the so-called angular placentation). The syncarpous gynoecium is usually derived from the apocarpous gynoecium with a cyclic (circular) arrangement of carpels, but in some cases it has also been derived from the spiral gynoecium. A good example of a syncarpous gynoecium is the lily and the tulip. At the first stages of the evolution of the syncarpous gynoecium, only the ovaries of the carpels grow together, and the columns (stylodia) remain free. But gradually, the process of fusion also captures the columns, which eventually grow together into one complex column, ending with a stigma head, which can be seen in heathers or in most monocots, including the lily.

Types of gynoecium

Monocarp (consists of one carpel). Forms a simple pistil. This type of gynoecium is typical for legumes.

Apocarpous gynoecium consists of several unfused pistils (magnolia, strawberry).

Cenocarpous - in the flower there is one complex pistil, consisting of fused carpels. The coenocarpous gynoecium is divided into syncarpous (the edges of the carpels are wrapped inward, forming an ovary divided into nests), lysicarpous (no partitions) and paracarpous (one-celled ovary with parietal placentation).

41. Flower formula. flower diagram

When compiling a flower formula, the following notation is used:

Calyx (Calyx) - Ca,

Corolla (Corolla) - Co,

Androecium (Androeceum) - A,

Gynoecium (Gynoeceum) - G,

Simple perianth (Perigonium) - P.

The type of flower is also taken into account:

Bisexual – ⚥

Pistillate - ♀

Staminate - ♁

Actinomorphic - ⁎

Zygomorphic - or ↓,

Asymmetrical - ↯

The number of members of each part of the flower is indicated by numbers. Five-lobed corolla Co5, six-membered androecium A6. If the number of flowers is more than 12 - sign ~ or ∞.

If members of the same name grow together, the number is enclosed in brackets (fused five-membered corolla - Co (5)). If the members of the same name are arranged in circles, then the numbers indicating the number of members in the circles are connected with a plus sign. (P(3+3))

To indicate the upper ovary, a dash is placed under the number of the number of carpels, the lower - above the number. For example, flower formulas:

A diagram is a schematic projection of a flower on a plane, in which the flower intersects across, perpendicular to its axis. Diagram design rule: inflorescence axis at the top, cover leaf at the bottom. Symbols of the diagram: parts of the perianth are indicated by arcs, sepals - with a protrusion in the middle of the arc, petals - without a protrusion. The stamens are indicated in the form of a cross-section of the anther or filament. Gynoecium - in the form of a transverse section of the ovary. If individual members grow together, this is indicated on the diagram by arcs.

42. Pollination of flowers. Its types and biological significance

Pollination of plants is the stage of sexual reproduction of seed plants, the process of transferring pollen from the anther to the stigma of the pistil (in angiosperms) or to the ovule (in gymnosperms).

At the same time, the stamens are male organs, and the pistil (ovule) is female - from it, with successful fertilization, a seed can develop.

Pollination types

There are two main types of pollination: self-pollination - when a plant is pollinated by its own pollen - and cross-pollination.

When cross-pollinated, plants can produce two main types of plants: monoecious and dioecious.

Cross-pollination requires the participation of an intermediary who would deliver pollen grains from the stamen to the stigma of the pistil; Depending on this, the following types of pollination are distinguished:

Biotic pollination (using living organisms)

Entomophily - pollination by insects; as a rule, these are bees, wasps, sometimes ants (Hymenoptera), beetles (Coleoptera), moths and butterflies (Lepidoptera), as well as flies (Diptera).

Bestiality - pollination with the help of vertebrates: birds (ornithophilia, pollination agents are birds such as hummingbirds, sunbirds, honeysuckers), bats (chiropterophilia), rodents, some marsupials (in Australia), lemurs (in Madagascar).

Artificial pollination - the transfer of pollen from the stamens to the pistils of flowers through human intervention.

Pollination of some plants from the pondweed family is sometimes carried out with the help of snails.

Animals that carry out pollination are called pollinators.

abiotic pollination

Anemophily - pollination by wind, is very common in grasses, most conifers and many deciduous trees.

Hydrophily - Pollination with water, common in aquatic plants.

About 80% of all plant species have a biotic type of pollination, 19.6% are pollinated by wind.

Geitenogamy - neighboring pollination, pollination of the stigma of the pistil of one flower, pollen from another flower of the same plant.

43. Adaptation of plants to different types and methods of pollination

Pollination is a necessary condition for the fertilization process that takes place in a flower. Pollen from the anthers is somehow transferred to the stigma of the flower. There are two types of pollination - self-pollination and cross-pollination (xenogamy) and several methods of pollination. If pollen is transferred within a given flower or individual, then self-pollination occurs. There are different forms of self-pollination: autogamy, when the stigma is pollinated by pollen from the same flower, geitopogamy (adjacent pollination), when the stigma is pollinated by pollen from other flowers of the same individual, and, finally, cleistogamy, when self-pollination occurs in closed, non-blooming flowers. These different forms of self-pollination are genetically quite equivalent.

If the transfer of pollen is carried out between the flowers of different individuals, then in this case cross-pollination occurs. Cross-pollination is the main type of pollination of flowering plants. It is characteristic of the vast majority of them.

In flowers, special devices of a morphological and physiological nature are very common, preventing or at least limiting self-pollination. Such are dioecy, dichogamy, self-incompatibility, heterostyly, etc. However, they also have adaptations for self-pollination, which contribute to the latter in the case when cross-pollination does not occur for some reason. In other words, the flower allows not only cross-pollination, but also self-pollination.

Cross-pollination is carried out in the following ways: with the help of insects (entomophily), birds (ornithophilia), bats (chiropterophilia) or agents of inanimate nature - wind (anemophilia) and water (hydrophilia). In accordance with this, one can speak of biotic and abiotic pollination.

Cross-pollination determines the exchange of genes and the integration of mutations, maintains a high level of heterozygosity in the population, and determines the unity and integrity of the species. This creates a wide field for the activity of natural selection.

Self-pollination, especially permanent, is considered as a secondary phenomenon caused by extreme environmental conditions unfavorable for cross-pollination. It then performs a protective function. Constant self-pollination is interpreted as a dead end of evolutionary development. In this case, the species is split into a series of pure lines and the processes of microevolution are attenuated. This correct but one-sided view of the evolutionary significance of self-fertilization reflected Darwin's idea that "nature abhors constant self-fertilization." This aphorism, as Charles Darwin himself pointed out (1876), will be erroneous if the word "permanent" is excluded from it. Pointing out the harmful effect of constant self-pollination, Darwin by no means denied its significance in general. In "Autobiography" (1887) he wrote: "I should have insisted more decisively than I did on the existence of numerous adaptations to self-pollination."

The negative value for the evolution of constant self-pollination is beyond doubt. However, it does not follow from Darwin's work that self-pollination always has negative consequences. According to modern ideas, for progressive evolution, both free crossing and some restriction of it are necessary. Cross-pollination increases the level of heterozygosity in the population, and self-pollination, on the contrary, causes its homozygotization. Self-pollination entails in essence the isolation of new forms, i.e., it separates and fixes in pure lines the favorable results of previous cross-pollination. This is the positive value for the evolution of the combination in a number of generations of self-pollination and cross-pollination.

The bisexuality and entomophily of the flower represent the primary phenomenon. In the flowers of the first angiosperms, along with a very primitive entomophily, self-pollination was probably also carried out. The bisexuality of the flower contributed to self-pollination, since adaptations to limit it were not yet developed.

44. General characteristics of inflorescences, their biological significance

inflorescences

Groups of flowers arranged close to each other in a certain order. Inflorescences are simple and complex. They usually contain small flowers, which makes them visible to pollinating insects.

The most common are the following inflorescences:

a) brush - cabbage, lily of the valley, bird cherry, lilac;

b) a simple ear - plantain;

c) a complex ear - rye, barley, wheat;

d) cob - corn;

e) a simple umbrella - cherry, apple, plum, primrose;

f) a complex umbrella - carrots, parsley, dill;

j) basket - sunflower, asters, sow thistle, dandelion;

g) head - clover, etc.

The biological meaning of the appearance of inflorescences:

1) an increase in the probability of pollination of flowers (in the inflorescence, small flowers are clearly visible);

2) sequential blooming of flowers in the inflorescence has certain biological advantages;

3) the type of inflorescence is associated with a certain type of infructescence and with devices for blooming fruits and seeds;

4) in saving material;

5) facilitates cross-pollination by wind.

45. Variants of classification of inflorescences according to one or more characteristics

Description and classification of inflorescences can be carried out according to various criteria. One of them is the nature of the foliage of inflorescences. On this basis, the following groups of inflorescences are distinguished:

Frondose (leafy) - veronica, violet.

Bracteous (scaly) - lily of the valley, lilac, cherry.

Ebracteous (bracts are reduced) - shepherd's purse and other cruciferous.

According to the degree of branching of the axes, simple and complex inflorescences are distinguished, the branching order of which exceeds one.

Back in 1826, it was proposed to divide the entire variety of inflorescences into two main categories according to the way the axes grow and the nature of branching. These categories are called differently by different authors.

Top flowers, definite and closed (cymose);

Side-colored, indeterminate and open (racemose, botric).

The terms primrose and lateral are probably the most expressive.

46. ​​Simple monopodial inflorescences, their common features and variants

Monopodial inflorescences are divided into simple and complex. In simple inflorescences, flowers are located directly on the axis of the first order (sessile) or on pedicels. Simple monopodial inflorescences (Fig. 10) include the following:

1. Brush - flowers on pedicels are arranged spirally on an elongated axis in the axils of bracts (lupins) or bracts are absent (cabbage, bird cherry, lily of the valley).

2. Shield - a brush in which flowers on pedicels depart from the main axis at different levels. The flowers are located in the same plane due to the unequal length of the pedicels (pear, hawthorn).

3. Simple ear - numerous flowers sessile on an elongated axis (vervain, plantain).

4. Earring - dangling ear, i.e. an ear with a soft axis, bearing same-sex flowers; after flowering, the inflorescence usually falls off completely (willow, poplar).

5. Cob - an inflorescence with a thickened axis and sessile lateral flowers. The ear is usually surrounded by one or more leaves (calamus, calla).

6. Umbrella - the main axis, shortened, and pedicels, having almost the same length, come out of very close nodes (susak, onion, cherry).

7. Head - an inflorescence with a shortened, club-shaped extended axis of the first order, pedicels or not or very short (clover).

8. Basket - an inflorescence with an axis expanded in the form of a disk and sessile tightly closed flowers. The apical leaves are crowded and form a wrapper (sunflower, chamomile, aster).

47. Complex monopodial inflorescences, their common features and variants

Complex inflorescences

A complex umbrella is similar in structure to a simple umbrella, but not pedicels come out of the short main axis, but branches (axes) of the second order, called rays. Small flowers grow on the rays on pedicels of the same length, forming umbrellas. (Cow parsnip, Annual Gill, Turkish Carnation)

A complex spike consists of a long main axis, on which second-order inflorescences grow - spikelets, similar in structure to a simple spike.

Panicle - so often called strongly branching inflorescences with a long main axis and second-order inflorescences, the lower of which are more branched and more strongly developed than the upper ones, which gives the entire inflorescence a pyramidal shape. (Plantain chastuha, Northern bedstraw, Panicled mullein) Partial inflorescences in a panicle may have a different structure, including similar to some of the simple inflorescences mentioned.

The curl is built like this: from the main axis with one flower grows another axis with one flower, from it - the third, and also with a flower, and so on, and they all face the same direction. (forest forget-me-not, rough comfrey, medicinal lungwort)

A forked inflorescence (fork) is described when the main axis at certain intervals branches into a pair of opposite branches of the second order

Cone. Basically it is an inflorescence (and a fruit) of coniferous plants. It is formed by scales arranged in the form of an ear, woody over time. Spores develop in male cones, while fertilization and seed maturation occur in female cones. The shapes of the cones are different - from almost round to cylindrical. In flowering (angiosperms) plants, cones are called capitate inflorescences, the covering leaves of which grow strongly and give the inflorescence the shape of a cone. Flowering plants do not have true cones (strobili).

The fantasy of nature knows no bounds, which is why sometimes inflorescences of a very complex and bizarre structure arise: spikelets collected in an umbrella, baskets in spike-shaped inflorescences forming a panicle, and others, and others. The main thing is not to get confused and see in the complex the familiar forms described above.

48. Sympodial inflorescences, their common features and variants

Sympodial inflorescences are divided into the following groups:

1. Monochasium - the growth of the main axis of the inflorescence is continued by one lateral axis of various orders. Monochasium occurs in the form of curls and convolutions. In the inflorescence, the curl of growth of the main axis continues with lateral axes of various orders in one direction (forget-me-not, comfrey, potatoes). During the formation of the gyrus inflorescence, the growth of the main axis continues with lateral axes of different orders in two directions (gladiolus, cuff, iris).

2. Dichasium (fork) - under the flower of the main axis, two opposite branches (axes) are formed, ending in a flower. In the future, each of these axes again forms two opposite branches of the next order (scapula, adonis).

3. Pleiochasia (false umbrella) - an inflorescence, from the main axis of which, bearing one apical flower, several lateral axes are formed, located in a whorl, outgrowing the main axis (euphorbia), and ending in flowers.

49. General characteristics of the fetus, its biological significance. Fruits are real and false, simple and complex. infructescence

Fruit (lat. fructus) - a flower modified in the process of double fertilization; an organ of reproduction of angiosperms, formed from a single flower and serving for the formation, protection and distribution of the seeds enclosed in it. Many fruits are valuable food products, raw materials for the production of medicinal, coloring substances, and so on.

FALSE FRUIT, a fruit that is formed not only in the wall of the OVARY, but simultaneously in other parts of the FLOWER. The false fruit may contain tissue from the CUP of the flower or the FLOWER. In strawberries, for example, the false fruit is the fleshy part, which becomes the receptacle, while the real fruits are the “seeds” planted in it. Other examples of false fruits are apple, fig, pear, and rosehip.

REAL FRUIT

A fruit that is formed only from the ovary. The remaining parts of the flower do not participate in its formation.

A simple fruit is a fruit that has developed from one pistil of a flower, and a complex one is a fruit that has developed from several pistils. Of the dry single-seeded fruits, such as a nut or a nutlet, an achene, a caryopsis, a lionfish are distinguished. Multi-seeded dry fruits are divided into drop-down (leaflet, bag, pod, box, bean, krynochka) and non-open, which in turn are jointed (joint pod and bean) and fractional (two-winged, visloped). Juicy fruits have a different color of the pericarp and can be either single-seeded (apple, berry) or multi-seeded (drupe).

50. Classification of fruits and its principles. Fruit groups and their characteristics

In most classifications, fruits are usually divided into real or true (formed from an overgrown ovary) and false (other organs also take part in their formation). Real fruits are divided into simple (formed from one pistil) and prefabricated, complex (arising from a polynomial apocarpous gynoecium). An example of prefabricated fruits: a complex nut or a multi-nut (rose hip), a complex achene (strawberry, strawberry), a complex drupe (raspberry), a frag or strawberry (a multi-nut on a fleshy receptacle that has grown when ripe). Complex fruits are named based on the names of simple fruits (multi-leaf, multi-drupe, multi-nut, and so on). Simple fruits are divided according to the consistency of the pericarp into dry and juicy.

I. Dry - with dry pericarp:

1. Box-shaped - multi-seeded

the box itself (poppy, tulip, dope);

krynochka;

bean (Family Legumes);

pod or pod (Cruciferous family);

leaflet.

Lionfish of palmate maple (Acer palmatum)

2. Nut-shaped or single-seeded

walnut, nut (hazel, hazelnut);

grains (cereals);

lionfish (maple);

acorn (oak);

achene (sunflower).

II. Juicy - with juicy pericarp:

1. Berry - multi-seeded:

berry (fruit of blueberry, currant, tomato);

apple (fruits of an apple tree, pear, mountain ash);

pumpkin (fruits of watermelon, pumpkin, zucchini);

hesperidium, or orange (citrus fruit);

pomegranate (fruit of the pomegranate).

2. Kostyankovidnye:

juicy drupes (cherries, plums, peaches);

dry drupe (walnut).

fruit plant groups

In total, more than 60 different breeds of fruit plants have been introduced into the culture.

Fruit plants according to the nature of the fruits and their economic use in production are conditionally divided into the following groups: pome, stone fruit, berry, grape, nut and subtropical fruit crops.

Pome breeds - apple, pear, quince, mountain ash, medlar, hawthorn, shadberry.

Stone fruits - cherries, sweet cherries, plums, thorns, thorns, cherry plums, apricots, peaches, dogwoods and almonds (almonds can be classified as nut fruits for economic use). Berry crops - gooseberries, currants (black, red, white), raspberries, blackberries, strawberries, strawberries. Gooseberries, currants are berry bushes, and raspberries and blackberries are semi-shrubs.

Grapes as a crop of great national economic importance, distinguished by its biological properties, are distinguished into a special group.

Nut crops - hazel, walnut, chestnut, pistachios.

Subtropical fruit crops - mandarin, lemon, orange, grapefruit, olive, pomegranate, persimmon, fig, etc.

51. Methods of distribution of fruits and plants Adaptive features of plants aimed at the distribution of fruits and seeds

At the beginning of the XX century. the Swedish botanist R. Sernander gave any parts of plants, with the help of which they are able to settle, the common name of diasporas. Seeds, fruits, seedlings, parts of the vegetative body, and even whole plants can act as diaspores. The main types of diaspores in seed plants are fruits and seeds; in lower and higher spores, spores.

There are two main ways of spreading diasporas. One - through the mechanisms developed in the process of evolution by the plant itself, the other - with the help of various external agents - wind, water, animals, humans, etc. The first type is called autochory, the second - allochory.

Plants are respectively called autochores and allochores.

Fruits and seeds of autochora are dispersed relatively close to the mother plant, usually no more than a few meters from it. The group of autochora plants is divided into mechanochora and barochora.

The fruits of many mechanochores are opened by nests or valves, and the seeds spill out of them. This is the case with tricolor violets (Viola tricolor), tulip species (Tulipa), etc. Some mechanochores actively scatter seeds thanks to special adaptations in fruits, which are based on increased osmotic pressure of the cells of the main tissue. The most common plants of this kind are common impatiens (Impatiens nolitangere), springy ekbalium, or mad cucumber (Ecballium elaterium). For short distances, the fruits of some clovers that have fallen to the ground can “creep away” due to the hygroscopic movements of the teeth of the calyx attached to the fruit.

Barochora are plants with heavy fruits and seeds. These include oak acorns (Quercus), walnut fruits (Juglans regia), horse chestnut seeds (Aesculus hyppocastanum). These seeds are shed from the mother plant and end up in close proximity to their parents.

The autochora group also includes geocarp plants. In geocarp species, the fruits in the process of development are introduced into the soil and ripen there. The most famous of them is the subterranean peanut, or peanut (Arachis hypogaea).

52. General characteristics of lower plants. Lifestyle features and evolution of algae, fungi, lichens

Lower plants, thallus, or thallus plants (lat. Thallophyta, Greek θάλλοφῠτόν: θάλλος - offspring, shoot, young branch, and φῠτόν - plant) - an informal term that unites those plants whose body, unlike higher plants, is not dissected into parts (root, stem, leaf).

The body of lower plants is called the thallus, or thallus; multicellular reproductive organs are absent.

Among the lower plants there are: unicellular, mostly microscopic, and multicellular, up to 40 m long, autotrophic algae (including lichens). Highly organized ones have a conducting system similar to the phloem of higher plants, leaf-like organs, the zygote develops into a multicellular embryo on the gametophyte (some brown algae). Fossil remains of a number of lower plants - unicellular algae - were found in Archean and Proterozoic deposits, which are about 3 billion years old.

Algae is a group of organisms of different origin, united by the following features: the presence of chlorophyll and photoautotrophic nutrition; in multicellular organisms - the absence of a clear differentiation of the body (called the thallus, or thallus) into organs; the absence of a pronounced conductive system; living in an aquatic environment or in humid conditions (in soil, damp places, etc.). They themselves do not have organs, tissues and are devoid of an integumentary membrane.

Some algae are capable of heterotrophy (feeding with ready-made organic matter), both osmotrophic (the surface of the cell), for example, flagellates, and by swallowing through the cell mouth (euglenoids, dinophytes). Algae sizes range from fractions of a micron (coccolithophorids and some diatoms) to 30-50 m (brown algae - kelp, macrocystis, sargassum). Thallus is both unicellular and multicellular. Among multicellular algae, along with large ones, there are microscopic ones (for example, kelp sporophyte). Among unicellular organisms, there are colonial forms, when individual cells are closely interconnected (connected through plasmodesmata or immersed in a common mucus).

Algae include a different number (depending on the classification) of eukaryotic divisions, many of which are not related by a common origin. Also, blue-green algae or cyanobacteria, which are prokaryotes, are often referred to as algae. Traditionally, algae are classified as plants.

The biological and ecological diversity of fungi is very high. This is one of the largest and most diverse groups of living organisms, which has become an integral part of all aquatic and terrestrial ecosystems. According to modern estimates, there are from 100 to 250 thousand, and according to some estimates, up to 1.5 million species of mushrooms on Earth. As of 2008, 36 classes, 140 orders, 560 families, 8283 used generic names and 5101 generic synonyms, 97 861 species are described in the kingdom Fungi.

The role of fungi in nature and in the human economy cannot be overestimated. Fungi are present in all biological niches - in water and on land, in soil and on various other substrates. Being decomposers, they play an important role in the ecology of the entire biosphere, decomposing all kinds of organic materials and contributing to the formation of fertile soils. The role of fungi as participants in mutually beneficial symbiotic (mutualistic) communities is great. There are known symbiotic relationships of fungi with higher plants - mycorrhiza, with algae and cyanobacteria - lichens, with insects, representatives of the neocallimastigos - an essential component of the digestive system of ruminants and some other herbivorous mammals, they play an important role in the digestion of plant foods.

53. Blue-green algae as typical representatives of prokaryotic organisms

Blue-green algae (Cyanophyta), pellets, more precisely, phycochrome pellets (Schizophyceae), slime algae (Myxophyceae) - how many different names this group of ancient autotrophic plants received from researchers! Passions have not subsided to this day. There are many such scientists who are ready to exclude blue-greens from among the algae, and some from the plant kingdom altogether. And not so, "with a light hand", but with full confidence that they are doing it on a serious scientific basis. Blue-green algae themselves are “guilty” of such a fate. The extremely peculiar structure of cells, colonies and filaments, interesting biology, great phylogenetic age - all these features separately and taken together provide the basis for many interpretations of the taxonomy of this group of organisms.

There is no doubt that blue-green algae are the oldest group among autotrophic organisms and among organisms in general. The remains of organisms similar to them are found among stromatolites (calcareous formations with a tuberculous surface and a concentrically layered internal structure from Precambrian deposits), which were about three billion years old. Chemical analysis found in these residues decomposition products of chlorophyll. The second serious evidence of the antiquity of blue-green algae is the structure of their cells. Together with bacteria, they are combined into one group called pre-nuclear organisms (Procaryota). Different taxonomists estimate the rank of this group differently - from a class to an independent kingdom of organisms, depending on the importance they attach to individual characters or the level of cellular structure. There is still much unclear in the taxonomy of blue-green algae, great disagreements arise at every level of their study.

Blue-green algae are found in all kinds of and almost impossible habitats, on all continents and water bodies of the Earth.

54. Department of Green Algae. General characteristics, structural features, representatives

Green algae (lat. Chlorophyta) is a group of lower plants. In modern systematics, this group has the rank of a division that includes unicellular and colonial planktonic algae, unicellular and multicellular forms of benthic algae. All morphological types of the thallus are found here, except for rhizopodial unicellular and large multicellular forms with a complex structure. Many filamentous green algae are attached to the substrate only in the early stages of development, then they become free-living, forming mats or balls.

The most extensive department of algae at present. According to rough estimates, this includes from 13,000 to 20,000 species. All of them differ primarily in the pure green color of their thalli, similar to the color of higher plants and caused by the predominance of chlorophyll over other pigments.

Structure

Algae have a green chloroplast containing, in addition to chlorophyll, a whole set of additional pigments, including xanthophylls - lutein, zeaxanthin, violaxanthin, antheraxanthin and neoxanthin and others. Additional pigments in green algae do not mask chlorophyll. The most important storage polysaccharide is starch, which occurs as granules around the pyrenoid or scattered in the stroma of the chloroplast. Pyrenoids are embedded in the chloroplast and pierced by thylakoids. The chloroplast has a double membrane. In this respect, green algae resemble red algae and higher plants. In chloroplasts, thylakoids are grouped by 2-6 in the form of plates, as in higher plants.

Flagella cells of green algae are isoconts - flagella have a similar structure, although they can vary in length. There are usually two flagella, but there may also be four or more. Flagella of green algae do not have mastigonemes (unlike heterokonts), but may have fine hairs or scales.

55. Department of Diatoms. General characteristics, structural features, representatives

Diatoms, or diatoms (lat. Bacillariophyta) - a group of chromists, traditionally considered as part of algae, characterized by the presence of a kind of "shell" in the cells, consisting of silica. Always unicellular, but colonial forms occur. Usually planktonic or periphytonic organisms, marine and freshwater.

Being the most important component of marine plankton, diatoms create up to a quarter of the entire organic matter of the planet.

Structural features

Only coccoids, the shape is varied. Mostly solitary, rarely colonial.

The cell wall is not homogeneous. Outside the shell, as well as inside it, there is a thin layer of organic matter.

Traditionally, diatoms are divided into two groups - pennate, with bilateral symmetry, and centric, with radial symmetry.

The first discovered representatives of diatoms were marine in origin and belonged to the centric type. Diatom shells from Early Cretaceous deposits are known with certainty. In the Late Cretaceous, the diatom flora was already rich and diverse in species composition; it consisted of almost 300 species and varieties belonging to 59 genera. But these were almost exclusively centric forms, having a rather primitive shell of two wings without a girdle. The valves were round, triangular, less often polygonal, with a structure of large areoles, often with large outgrowths, spines, and bulges, which facilitated the association of cells into a colony. Most of the ancient genera were monotypic or included 2-3 species each. Diatoms of this period, apparently, did not have wide ecological plasticity, but were stenohaline and stenothermic, which contributed to their rapid extinction. Some genera became extinct by the end of the Cretaceous.

56. Department Brown algae. General characteristics, structural features, representatives

Brown algae (lat. Phaeophyceae) - a department of autotrophic chromists. In the life cycle of all representatives there are multicellular stages. Mostly marine forms, only seven species have moved to existence in fresh water.

Brown algae include 1500-2000 species, which are united in 265 genera, of which Laminaria (Laminaria), Sargassum (Sargassum), Cystoseira (Cystoseira) are well known.

Brown algae in chromatophores contain the brown pigment fucoxanthin (C40H56O6). This pigment masks the rest of the pigments.

Unlike other algae, brown algae are characterized by unicellular hairs with a basal growth zone.

Some brown algae, such as wakame, are edible.

Brown algae - a department of true multicellular algae of brown color. This group of plants includes 250 genera and about 1500 species. The most famous representatives are kelp, cystoseira, sargassum.

These are mainly marine plants, only 8 species are secondary freshwater forms. Brown algae are ubiquitous in the world's seas, reaching a special diversity and abundance in cold water bodies of subpolar and temperate latitudes, where they form large thickets in the coastal strip. In the tropical zone, the largest accumulation of brown algae is observed in the Sargasso Sea, their mass development usually occurs in winter, when the water temperature drops. Extensive underwater forests are formed by kelp off the coast of North America.

57. Department Red algae.General characteristics, structural features, representatives

Red algae, or Bagryanka (lat. Rhodóphyta) - inhabitants primarily of marine reservoirs, few freshwater representatives are known. Usually these are quite large plants, but microscopic ones are also found. Among the red algae, there are unicellular (extremely rare), filamentous and pseudoparenchymal forms; true parenchymal forms are absent. Fossil remains indicate that this is a very ancient group of plants.

Red algae are eukaryotes.

Chloroplasts of red algae are two-membrane, with single thylakoids. One or two thylakoids usually lie on the periphery of the chloroplast. Thylakoid membranes contain phycobilisomes. Chlorophyll is the main pigment in chloroplasts. In addition, red algae have carotenoids and phycobilins in phycobilisomes. Thanks to this set of pigments, red algae can absorb light from almost the entire visible part of the spectrum. As a rule, chlorophyll is masked by phycobilins (red and blue) and carotenoids (orange-yellow), but there are exceptions among freshwater red algae. So, Batrachospermum, which lives in sphagnum bogs, is blue-green in color.

According to various sources, today there are from 5,000 to 10,000 described species of red algae. Almost all of them belong to seaweeds. About 200 freshwater species have been described, among them:

Atractophora hypnoides

Gelidiella calcicola

Palmaria palmata

Schmitzia hiscockiana

Chondrus crispus

Mastocarpus stellatus

58. Mushrooms. The place of fungi in the system of heterotrophic organisms

Mushrooms (lat. Fungi or Mycota) is a kingdom of wildlife that unites eukaryotic organisms that combine some features of both plants and animals. Mushrooms are studied by the science of mycology, which is considered a branch of botany, since mushrooms were previously attributed to the plant kingdom.

The concept of mushrooms as a separate kingdom was formed in science by the 1970s, although E. Fries proposed to single out this kingdom in 1831, and Carl Linnaeus expressed doubts when he placed mushrooms in the plant kingdom in his System of Nature. In the second half of the 20th century, the idea of ​​fungal polyphyletism was finally formed. By the end of the 20th century, data on genetics, cytology and biochemistry had been accumulated, which made it possible to divide this group of organisms into several unrelated branches and distribute them between different kingdoms, leaving only one of them in the kingdom of "real", or fungi proper.

Mushrooms are ancient heterotrophic organisms that occupy a special place in the general system of living nature. They can be both microscopically small and reach several meters. They settle on plants, animals, humans or on dead organic remains, on the roots of trees and grasses. Their role in biocenoses is great and varied. In the food chain, they are decomposers - organisms that feed on dead organic residues, subjecting these residues to mineralization to simple organic compounds.

59. Lower mushrooms. Order Oomycetes, Zygomycetes

Lower fungi - all departments related to fungi, except for ascomycetes (lat. Ascomycota), basidiomycetes (Basidiomycota) - departments of the sub-kingdom of higher fungi (Dikarya) - and deuteromycetes (Deuteromycota). Characterized by non-cellular, non-septate mycelium (mycelium); in the most primitively organized chytridiomycetes, the vegetative body is a naked protoplast. Sometimes fungal hyphae are not formed, but plasmodium appears - an overgrowth of the cytoplasm with many nuclei.

Zygomycetes (lat. Zygomycota) is a department of fungi that unites 10 orders, 27 families, about 170 genera and more than 1000 species. They are distinguished by a developed coenocytic mycelium of variable thickness, in which septa are formed only to separate the reproductive organs.

60. Higher mushrooms. Class Ascomycetes, Basidiomycetes

Higher mushrooms (lat. Dikarya) - a sub-kingdom of fungi, which includes Ascomycetes and Basidiomycetes. In everyday life, it is the higher mushrooms (or their fruiting bodies) that are usually called mushrooms. The Latin name of the subkingdom is due to the fact that during sexual reproduction, the representatives of these departments form binuclear cells (dikaryons) and even dikaryotic mycelium, and only after some time the nuclei merge, giving rise to a diploid zygote

Ascomycetes (from Greek ἀσκός - bag), or marsupials (lat. Ascomycota) - a department in the kingdom of fungi that combines organisms with septate (divided into parts) mycelium and specific organs of sexual sporulation - bags (asci), most often containing 8 ascospores. They also have asexual sporulation, and in many cases the sexual process is lost and these types of fungi are classified as imperfect fungi (Deuteromycota).

Ascomycetes include up to 2000 genera and 30,000 species. Among them - yeast (class Saccharomycetes) - secondarily unicellular organisms. Other well-known representatives of ascomycetes include morels, parmelia, stitches and truffles.

Basidiomycota (lat. Basidiomycota), basidiomycetes, or basidial fungi - a department of the fungal kingdom, including species that produce spores in club-shaped structures called basidia. Together with ascomycetes, they belong to the sub-kingdom of higher fungi (Dikarya).

61. Lichens are specific symbiotic organisms. The place of lichens in the system of organisms

Lichens (lat. Lichenes) - symbiotic associations of fungi (mycobiont) and microscopic green algae and / or cyanobacteria (photobiont, or phycobiont); the mycobiont forms a thallus (thallus), inside which the photobiont cells are located. The group includes about 400 genera, including from 17,000 to 26,000 species.

1. The place of lichens in the system of the organic world: an independent group of complex symbiotic organisms that cannot be attributed to plants, animals, or fungi. The structure of the lichen: the body - the thallus consists of filaments of the fungus, between which there are unicellular algae. Symbiosis of fungus and algae. Heteroautotrophic lichen nutrition: algae synthesize organic substances from inorganic substances using solar energy, and fungal hyphae absorb water and mineral salts from the environment.

The manual outlines general issues of the biology of vegetable crops, provides up-to-date data on the state of the industry in the country and abroad. The book fully discloses the nutritional and medicinal value of vegetables. The biological foundations of vegetable growing are described in detail: the classification of vegetable plants, their centers of origin, the characteristics of the growth and development of vegetable plants, depending on environmental factors (heat, light, moisture, nutrition, etc.) that determine their vital activity.

The manual is intended for university students studying in the direction of "Agronomy". Approved by the educational and methodological association of universities of the Russian Federation for agronomic education as a teaching aid for students studying in the direction of "Agronomy"

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The plant begins its life journey with the germination of the seed, from which the main organs are formed: root, stem, leaf, flowers, fruits and seeds (see Fig. 2).

Rice. 2. The structure of the plant

When a seed germinates, an embryonic root first appears, which later turns into a developed root system.

Root- the main underground vegetative organ of the plant.

The root anchors the plant to the soil and provides the plant with resistance to the wind; absorbs and delivers water to plants with soil minerals dissolved in it; often serves as a reservoir of reserve nutrients; serves as a reproductive organ in the presence of adnexal buds.

There are three types of roots. main root develops from the germinal root of a germinating seed, has a vertical position in the soil, deepening its end into the lower soil layers.

On the sides of the main root from it appear lateral roots of the first order, from them the roots of the second, then the third order, etc.

adventitious roots arise not from the main or lateral roots, but from parts of the shoot, i.e., the stem (tomato, cucumber, pumpkin, etc.), leaves or on modified stems: rhizomes (asparagus, horseradish, rhubarb), tubers (potatoes), bulbs (onion garlic). The successful emergence of adventitious roots is facilitated by the contact of parts of the stem and leaves with moist soil.

The root system is rod, where the main root reaches a powerful development and stands out sharply in thickness and length in the mass of lateral and adnexal (tomato, sorrel); fibrous, consisting of a mass of adventitious roots (onion, cucumber, lettuce) and root varieties - cone-shaped, fusiform, onion - are found in beets, carrots, rutabaga, turnips, etc. - small rounded outgrowths - nodules are formed on the roots of leguminous plants. Nodule bacteria assimilate free nitrogen from the air and turn it into compounds available to plants.

The roots of many vegetable plants are used for food (all root crops).

The aerial part of a plant stem with leaves developing on it is called escape. Together with the side shoots, it makes up the skeleton of the plant. The stem performs supporting (mechanical) and conducting functions. The stem carries out two-way movement of nutrients from the roots to the leaves and from the leaves to other organs.

The stem consists of nodes (the place where leaves are attached to the stem) and internodes (sections of the stem between the nodes), bears buds, leaves, flowers and fruits. The angle between the stem and the leaf at the point of departure is called the leaf axil. Every shoot develops from a bud, therefore, a bud is a rudimentary shoot. The place where the stem meets the root is called the root collar. The length of the internodes is very short. An example of a shortened shoot is a bud, and for adult shoots - a head of cabbage, a rosette of basal leaves of root crops in the first year of life.

By the nature of growth, the stem is upright (tomato, pepper), rising, creeping, creeping (whips of cucumber, pumpkin), curly (beans).

Rice. 3. The structure of the stem in various vegetable plants

All vegetable plants have a herbaceous stem (see Fig. 3).

Rhizome- a modified thickened underground part of the stem, serves for vegetative propagation and provides a supply of nutrients (horseradish, asparagus).

Tuber- a modified stem that has several internodes (potato).

Bulb- an underground strongly shortened shoot with a short flat stem - bottom and leaves - fleshy scales.

A leafless stem ending in an inflorescence is called flower arrow(onion).

Sheet is an organ of assimilation, gas exchange and evaporation. A green leaf synthesizes organic substances that are involved in building a plant and in all chemical transformations.

The leaf is connected to the stem by a petiole. Simple leaves have one leaf blade, complex leaves have several blades, each with its own petiole. The petiole is continued in the form of the central vein of the leaf with numerous branches. The veins are the vessels of the leaf. The petiole of the leaf serves as an organ for orienting the leaf in relation to the light and helps to weaken the impact on the leaf plate from rain, hail, wind, etc. The tendril is a modified leaf (cucumber, pumpkin), it also participates in photosynthesis.

The leaves of some plants have pubescence that performs various functions. It reduces the contact of the leaf with the air flow, preventing excessive evaporation, repels herbivores, or reflects sunlight, preventing overheating.

The green color of the leaf becomes due to the large amount of chlorophyll contained in the chloroplasts.

The leaves are very diverse in the shape of the plate (round, heart-shaped, ovate, lanceolate, etc.), the edge of the leaf (toothed, serrated, lobed, etc.), the type of venation (pinnate, palmate, parallel), the type of attachment to the shoot (petiolate , sessile, enclosing). On the stem, the leaves are placed spirally, or alternately (one leaf leaves from each node of the stem), opposite (two leaves are attached to each node opposite each other), whorled (three or more leaves are located at each node).

Flower- Plant reproductive organ. Flowers are bisexual - with a pistil and stamens, and separately hollow - only with a pistil (female) or only with stamens (male). Flowers can be solitary or collected in short or branched inflorescences.

A monoecious plant has bisexual (family nightshade) or dioecious (family pumpkin) flowers. If male flowers are located on one plant, and female flowers on another, then such plants are called dioecious (asparagus, spinach, some varieties and hybrids of cucumber). There are two biological types of pollination: self-pollination and cross-pollination. Self-pollination occurs in bisexual flowers, when pollen from the anthers spills out on the stigma of its own flower (fam. Solanaceae). Cross-pollination is carried out with the help of insects (family gourds, fam. onions) or wind. In wind-pollinated corn plants, the panicles of male flowers produce a lot of pollen that is carried by the wind over long distances. Insect-pollinated flowers have a liquid sugary secretion that attracts insects. At the same time, the pollen of many plants serves as food for insects.

Fetus- this is the lower or upper ovary that developed after pollination and fertilization of the flower, inside which the seeds are located. Parthenocarpy - the property of some plants to form a fruit without pollination. Usually these are seedless fruits or with underdeveloped seeds. This property of plants is widely used in breeding.

Juicy fruits. pumpkin, nightshade, legumes are used for food in technical maturity (cucumber, zucchini, eggplant, peas, young beans, sweet corn) and biological maturity (tomato, pepper, physalis, pumpkin, watermelon, melon). Unripe fruits, except for eggplant and corn, are rich in chloroplasts. The color of juicy ripe fruits is associated with anthocyanins and chromoplasts.