Vegetative organs. Plant organs Seed vegetative organ

Concept of plant organs

Definition 1

Organ- this is a part of a plant organism adapted to perform one or more functions.

In plants, there are two groups of organs interconnected into an integral system - vegetative and generative.

Vegetative ones include the root and shoot, consisting of a stem, leaves and buds, and generative ones include a flower, fruit and seed (in spores it is a sporangium, in gymnosperms it is a cone).

Vegetative organs of plants

Definition 2

Vegetative organs (from the Latin vegetativas - plant) in plants are those that support the basic life processes, that is, they perform the main functions of its nutrition and metabolism with the environment.

These organs were formed as a result of the dismemberment of a homogeneous body of lower plants (algae) - thalom. The reason for this was the transition from an aquatic to a terrestrial way of life.

One of the common features of vegetative organs is their polarity. Each organ has two poles: the upper, or apical, and the lower, or main. Vegetative organs are able to orient themselves in space in a certain way: the root always grows towards the center of the Earth (positive geotropism), the stem always grows from the center of the Earth (negative geotropism). The axial organs - stem and root - are located vertically to the surface of the Earth (orthotropic organs) and the leaves - at an angle (plagiotropic organs). This specialization is due to two areas of plant nutrition (soil and atmospheric), and therefore, a two-way flow of water with dissolved minerals and organic substances.

The root has unlimited growth and has no leaves. Provides absorption and transportation of water and compounds dissolved in it, synthesis (and often storage) of substances, and respiration.

Stem in typical cases - an axial polysymmetric organ of unlimited growth. The stem provides a connection between the leaves and roots, promotes the formation of a strong assimilation surface of the leaves and their best placement relative to the light, and stores nutrients.

Sheet- a lateral organ of limited growth, grows at the base by intercalary growth (in monocots) or over the entire surface (in dicots). The leaf consists of a leaf blade and petiole, stipules; leaves without a petiole are called sessile (rye). In annual plants, the life span of the leaf is similar to the life span of the stem. In trees and bushes it is a temporary organ. The main functions of the leaf: photosynthesis, gas exchange, transpiration, reproduction, protective (spines), cleansing (leaf fall), nutrition (sundew).

Note 1

Vegetative organs do not take part in sexual reproduction, but they can still contribute to the so-called vegetative method of plant propagation (with the help of rhizomes, tuber bulbs, tendrils, etc.). With this method of reproduction, a new organism grows from the multicellular part of the mother organism.

The division of the plant body into organs and the formation of a large number of branches, leaves and roots made it possible to develop a huge photosynthetic surface and absorb a sufficient amount of water and mineral elements.

Generative organs of plants

Definition 3

Generative (reproductive) organs(from lat. genero - giving birth) plants arose much later than vegetative ones. The flower, seed and fruit that are formed from it are considered the highest achievement of the process of reproduction in the plant world. Thanks to the generative organs, the process of sexual reproduction is ensured.

The generative organs of flowering plants are flowers, due to which fruits and seeds are formed. The process of sexual reproduction in flowering plants occurs when the plant flowers (the flowers open).

Flowers are very diverse in shape, size, color and structural features. However, the basic structure and processes of flower development are identical in all plants. The flower has stamens, pistils and perianth (petals and calyx). The main function of the stamens is the formation of pollen grains with male reproductive cells (sperms). The pistils contain the seed buds, and they contain the female reproductive cells (eggs).

From the seed germ, as a result of fertilization, a seed is formed, inside of which there is an embryo and endosperm under the skin. The seeds are surrounded by a pericarp, which is formed from the walls of the ovary. Together, the seeds and pericarp form the fruit. After a period of dormancy, the seeds germinate under favorable conditions and a young plant develops from them.

Note 2

The generative organs of spore plants - mosses, horsetails, ferns - have a different structure.

Plant organs

Plants have the following organs: root, shoot, consisting of stem, leaves and buds, flower, seed, fruit. All of the above organs are found only in angiosperms; Gymnosperms have no flower and fruit, ferns have no flower, seed and fruit, and bryophytes have only a shoot. The root and shoot are vegetative organs, the rest are generative. Vegetative organs are responsible for the nutrition and metabolism of the plant, i.e. ensure its existence. Generative organs carry out seed propagation of plants. Sometimes the term “reproductive organs” is used - these are organs used for reproduction, i.e. These include both vegetative and generative organs.

ROOT

A root is a vegetative axial organ of a plant, which has radial symmetry and is most often found in the soil. Generative organs and leaves never form on plant roots.

Functions:

1. Absorption of water and minerals.
2. Support.
3. Supply of nutrients.
4. Synthesis of organic substances (phytohormones, alkaloids).

Types of roots

1. Main (develops from the embryonic root of the seed).
2. Adjuncts (develop on underground or aboveground parts of the shoot).
3. Lateral (occur during lateral branching of roots, i.e. they develop on the main, adventitious and lateral roots).

All roots of the plant form root system- rod or fibrous. Dicotyledonous plants have a tap root system (except: great plantain), while monocotyledonous plants have a fibrous system. Taproot - the main root is clearly defined (bean, maple). The taproot system is formed mainly by the main and lateral roots. Fibrous – the main root is poorly developed or absent (wheat, onion). The fibrous root system is mainly formed by adventitious and lateral roots.

Root structure. Root structure in a longitudinal section. The root apex is covered with a root cap (these are living cells that protect the apical meristem of the root). Starting from the root apex, the following zones are distinguished:

1. The division zone is located immediately under the cover.
2. Growth zone.
3. Suction zone.
4. The conduction zone in which lateral roots form.

Root structure in cross section. In the division zone there are cells of educational tissue that ensure the growth of the root in length. In the growth zone, individual cells continue to divide, and differentiation of the integumentary, main and conductive root tissues also begins.

In the absorption zone, rhizoderm cells have outgrowths - root hairs, through which plant roots absorb water and minerals from the soil. Thanks to root hairs, the absorption surface increases 10 times or more. The root hair has a large vacuole, the nucleus is located at the tip of the hair. Under the rhizoderm is the cortex, consisting of thin-walled living cells. At the center of the root is a central cylinder of bast and wood. The core is not formed at the root.

In the conduction zone between the wood and the bast, a cambium appears, which is responsible for growth in thickness. The bark tissues cannot follow the secondary thickening and die, and thanks to the work of phellogen, a new covering tissue, a plug, appears on the root surface.

Absorption of water and mineral salts by roots occurs in all zones of the root, but is most active in the absorption zone. From the root hairs, water and mineral salts enter the root bark, and from it into the wood, through which further transport takes place to the stem. There are two ways for water and substances dissolved in it to enter: through cell walls or through the living contents of cells. Osmosis is the absorption of water by a more concentrated solution into the cell. Thanks to osmosis, it is created root pressure– a force that promotes the one-way movement of water along the xylem from bottom to top (from root to stem).

Breathing of roots. The root absorbs oxygen and releases carbon dioxide during respiration. This is confirmed by the following experiment: if you place the root of a plant in a test tube for a while, then take it out and put a burning match into the test tube, the match will go out almost instantly.

Root modifications

1. A root vegetable is an organ in the formation of which the lower part of the stem and the main root (carrots, beets, turnips, radishes) participate. The main function of the root vegetable is to store nutrients.
2. Root tubers or root cones are thickening of adventitious roots (dahlia, sweet potato, chistyak). The main function is the supply of nutrients and vegetative propagation.
3. Bacterial nodules (legumes) are thickenings on the roots that contain bacteria. Bacteria convert nitrogen from the atmosphere into substances that are absorbed by the plant; the plant provides bacteria with organic substances, i.e. this is an example of symbiosis.

Human influence on plant root systems

Soil cultivation. When digging, the soil structure improves, the roots are located throughout the plowed horizon, where they receive the required amount of water and air. When loosening the top layer of soil (cultivation), the soil crust is destroyed and the water and air conditions improve.

Watering. Should be uniform and sufficient. There is a direction in agriculture - hydroponics, when plants are grown in aqueous nutrient solutions without soil.

Picking – removal of the top of the main root. The root system becomes more powerful and develops in the upper, most fertile horizon.

Fertilizers. There are mineral and organic fertilizers. Mineral fertilizers are divided into nitrogen (nitrate, urea), phosphorus (superphosphate, double superphosphate), potassium (potassium sulfate, potassium chloride), complex (contain phosphorus, nitrogen and potassium, for example nitrophoska) and microfertilizers (contain microelements - zinc, iron, boron , molybdenum). Organic materials include manure, peat, and bird droppings (guano). Nitrogen fertilizers are responsible for the growth and faster development of plants (increase in vegetative mass). Potash helps improve the quality of fruits, enhances plant resistance to certain diseases, and increases frost resistance and drought resistance. Phosphorus improves the growth of the root system, increases the yield and improves its quality, accelerates the ripening of plants, and increases their resistance to drought. Microfertilizers promote the synthesis in the plant of substances necessary for growth and development. All fertilizers are applied in strictly defined quantities. Nitrogen fertilizers are applied in the spring, potassium and phosphorus fertilizers are usually applied in the fall. The use of fertilizers is possible in dry form (in the spring before sowing or in the fall when digging) and in liquid form - root and foliar feeding (solutions with a concentration of no more than 10% and 1%, respectively) during the growing season.

THE ESCAPE

This is an organ consisting of a stem, leaves and buds and is most often located in the ground-air environment. Knot- this is the section of the stem on which the leaf and axillary bud are located. internode- this is the section of the stem between two adjacent nodes. The angle formed by the leaf and the stem located above is called leaf axil.

Types of shoots

1. Erect - the stem occupies a vertical position.
2. Creeping - the stem occupies a horizontal position.
3. Creeping - the stem takes a horizontal position, and adventitious roots form on it (meadow tea).
4. Curly (beans).
5. Clinging (ranks).
6. Depending on the severity of the internodes: shortened and elongated.

Bud

A bud is an embryonic shoot.

Types of kidneys

1. According to their position on the stem, there are apical (at the top of the shoot) and lateral or axillary buds (located in the axil of the leaves).
2. Based on the presence or absence of bud scales - closed (there are bud scales - oak, poplar, linden) or open buds (no bud scales - clover, buckthorn, elodea).
3. According to the nature of the internal contents - vegetative, generative (floral, cherry) and mixed buds (elderberry, lilac). Vegetative buds contain the rudiments of only vegetative organs, generative - only generative, mixed - both generative and vegetative.
4. Accessory buds. They are found on the internodes of stems, on leaves and on roots.
5. Dormant buds located on the stem, but not opening immediately after formation. They are, as it were, a reserve of shoots (it is precisely because of the presence of dormant buds that poplars form new shoots after severe pruning).

Kidney structure. On the outside, most buds are covered with bud scales, which protect the bud and protect its internal contents from drying out. Inside are the rudiments of all plant organs: rudimentary leaves, rudimentary stem, rudimentary buds. Also inside the bud may contain the rudiments of future flowers. At the top of the embryonic stem there is a growth cone - this is educational tissue.

SHEET

A leaf is a vegetative organ of a plant, occupying a lateral position and providing aerial nutrition to the plants. Unlike other vegetative organs, the leaf is not characterized by unlimited (i.e. throughout its life) growth. Functions: f otosynthesis, water evaporation, gas exchange.

External leaf structure. The leaf consists of a base, petiole, leaf blade and stipules. The stipules can grow together, enveloping the stem - this forms a bell (sorrel). The base is the part of the leaf by which the leaf is attached to the stem. If the base grows and covers the stem, then a leaf sheath is formed (wheat, corn, wheatgrass).

Types of leaves. Depending on the number of leaf blades, leaves are divided into simple(one leaf blade, there is no articulation between it and the petiole) and complex(one or many leaf blades separated from the common petiole). Among the compound leaves there are: trifoliate (clover, strawberry, oxalis), palmate (horse chestnut), paripirnate (yellow acacia) and imparipinnate (ash, rowan, rose hip).

Venation is the arrangement of conductive bundles (veins) in the leaf blade. Happens:

1. Cirrus (lilac, birch, linden).
2. Finger (cuff, maple).
3. Dugovoe (large plantain, lily of the valley).
4. Parallel (rye, corn, bluegrass).

Leaf arrangement- This is the order in which the leaves are placed on the stem. There are:

1. Regular leaf arrangement - only one leaf emerges from each node (birch, poplar, oak).
2. Opposite leaf arrangement - two leaves emerge from each node (lilac, maple, elderberry).
3. Whorled leaf arrangement - three or more leaves emerge from each node (oleander, raven's eye, elodea).

Sheet mosaic. Leaf mosaic is the arrangement of plant leaves in one plane. The leaves in the mosaic are arranged horizontally, while the leaves have different sizes and practically do not shade each other, which allows for maximum use of solar energy.

Internal structure of the leaf. On the outside there is a covering tissue - the epidermis. The stomata are located mainly on the lower side of the leaf (in aquatic plants with floating leaves (water lily), on the contrary, the stomata are mainly located on the upper side of the leaves). The integumentary tissue of the leaf secretes a special layer consisting of waxes - the cuticle, which reduces evaporation from the surface of the leaf.

Between the upper and lower epidermis is the main leaf tissue, which consists of columnar and spongy parenchyma. Columnar (palisade) parenchyma is located under the upper epidermis and is formed by cells elongated in a perpendicular direction to the epidermis. Spongy parenchyma is located under the columnar tissue and consists of loosely arranged cells with a large number of intercellular spaces.

The leaf veins (vascular bundles) do not contain cambium. The wood is located closer to the upper surface of the leaf, and the bast is closer to the lower surface. Mechanical tissue is usually located outside the conductive bundle.

Processes occurring in the sheet

1. Photosynthesis – This is the process of formation of organic substances from inorganic substances using sunlight.
2. Gas exchange in plants occurs in the leaves through stomata. During the day, both carbon dioxide and oxygen enter the plant, and both oxygen and carbon dioxide are released, i.e. During the day, two processes occur in parallel in plant cells - photosynthesis and respiration. At night, photosynthesis does not occur; respiration occurs in the cells (mainly due to the oxygen contained in the intercellular spaces).
3. Evaporation of water. The release of water by the plant occurs through the stomata of the epidermis. This cools the plant, which prevents overheating; in addition, a continuous flow of water from the roots to the leaves is maintained. Plants can protect themselves from excessive evaporation in the following ways: reduction and (or) modification of the leaf blade (feather grass, cactus); well-developed cuticle (agave); a large number of hairs in the epidermis (Saintpaulia).
4. Leaf fall is the natural falling of leaves. In this regard, plants are divided into deciduous and evergreen. Evergreen plants are characterized by perennial leaves (pine leaves live 2-4 years, spruce leaves - 5-7 years). Deciduous plants lose all their leaves annually at the end of the growing season (oak, birch, maple). By the end of summer - beginning of autumn, the leaves begin to age, the intensity of metabolism in them decreases, chlorophyll and chloroplasts begin to break down, the leaves acquire a different color (not in all plants: for example, lilac leaves remain green). A separating layer of cells consisting of dead cork cells begins to form between the base of the leaf and the stem. At this time, a bud is finally formed in the leaf axil, after which the leaf falls off. The mark left by a fallen leaf on a stem is called a leaf scar. The meaning of leaf fall: removal of unnecessary substances from the body; reduction of evaporation, which is especially important in winter, when the flow of water from the soil practically stops; reducing the mass of shoots and their area, which reduces the amount of snow retained on the branches, therefore reducing the likelihood of shoot breakage.

Leaf modifications

1. Spines – develop in plants living in conditions of insufficient moisture (cactus)
2. Antennae (peas, chin).
3. Trapping devices of insectivorous plants (sundew).
4. Scales are small, underdeveloped leaves (lily of the valley, peas).

Stem

The stem is the axial part of the shoot. Functions: support, transport of substances, storage of substances, photosynthesis (in young stems of trees and shrubs, as well as in grasses).

Internal structure of the stem (using the example of linden)

Primary structure of the stem:

a) Primary cortex. On the outside is the epidermis, under which the main photosynthetic tissue is located. In addition to these tissues, the primary cortex also includes mechanical tissues (usually collenchyma).

b) A central cylinder in which conductive tissue and core are isolated. Conductive tissues are represented by xylem and phloem; they form conducting bundles. The core consists of living cells.

Secondary structure of the stem. Its appearance is associated with the laying of the cambium and the replacement of one type of integumentary tissue (epidermis) with another (periderm). The secondary structure of the stem includes the following sections: secondary bark (cork and bast), cambium, wood and pith.

Development of shoot from the bud. Branching. In spring, sap flow begins in the plants, and the necessary substances enter the buds. The cells of the growth cone begin to actively divide, the rudimentary stem increases, the bud scales move apart and gradually fall off, and a bud ring forms in their place. The shoot grows and develops, new leaves and new buds form on it. A shoot that has developed from a bud in one growing season is called annual growth.

During the development of the shoot, its branching occurs. Branching is the formation of new shoots located at an angle to each other. There are two types of branching: apical and lateral. Apical branching is carried out due to the division of the apical educational tissue into two parts (the so-called dichotomous branching) and is characteristic of lycopods. With lateral branching, new shoots arise from the lateral buds. A type of lateral branching is tillering, in which the formation of new shoots occurs from axillary buds located at the base of the main shoot (cereals, shrubs).

Stem growth. In length it is carried out due to the division and subsequent growth of cells of the apical and (or) intercalary educational tissues. Growth in thickness occurs due to the activity of the cambium. The work of the cambium is periodic: in spring and early summer it is intense, and by the end of the growing season it subsides. The cambium deposits more cells towards the wood. At the beginning of the growing season, the cambium forms vessels with a large lumen; few mechanical elements are formed; by the end of the growing season, the lumen of the newly formed vessels decreases and more mechanical elements are formed. On a cross-section of a tree, these differences are visible to the naked eye in the form of growth rings. The annual ring is the growth of wood over the year based on the thickness of the stem. The age of the plant can be determined by the growth rings.

Transport of substances

1. Water moves through the wood with substances dissolved in it (mainly mineral substances, but organic substances that are synthesized or accumulated in the roots also move) from the bottom up. At the beginning of spring, a solution with a predominance of organic substances moves through the wood.
2. Dissolved organic substances move through the bast in both directions: from leaves to roots (top to bottom) and from leaves to fruits and flowers (bottom to top).

Modifications of shoots:Overhead

1. Thorns (hawthorn) - perform protective functions.
2. A tendril is a modified leaf (pea) or the entire shoot (grape). Function: twisting around a support, holding the shoot in a vertical position.
3. The aboveground stolon is an elongated creeping shoot. It lives for less than a year and performs the function of vegetative propagation: a shortened shoot (“rosette”) is formed at the top of the stolon, which takes root, and a new plant develops from it (tenacious, strawberry).
4. A head of cabbage is a modified bud (cabbage).

Underground

1. Underground stolon. Performs the function of dispersal and vegetative propagation. Formed from buds at the base of the stem; usually white in color with colorless scale-like leaves. In plants such as potatoes and rosemary, a tuber is formed at the end of the stolon.
2. Tuber is a highly thickened underground shoot (potato, Jerusalem artichoke, corydalis, sedum). Performs the function of a supply of nutrients, ensures survival of unfavorable conditions, vegetative propagation and renewal.
3. A bulb is an underground shoot with a very short, flattened stem (bottom) and succulent leaves (lily, tulip, onion). Performs functions: supply of nutrients, survival of unfavorable conditions, renewal, vegetative propagation.
4. A corm is an underground shoot of plants. It has dry, filmy leaves, and reserve nutrients are deposited in the stem (crocus, gladiolus, colchicum).
5. Rhizome is an underground or aboveground modified perennial shoot with scale-like or green leaves. Responsible for reproduction, settlement, supply of nutrients, renewal and waiting out unfavorable environmental conditions (wheatgrass, lily of the valley, iris).

It is impossible to imagine the earth's landscapes without plants. They play an important role in the planet's ecosystem, maintaining the necessary oxygen content in the air and creating a fertile layer of soil. The vegetative organs of plants help them perform basic life functions and interact with the environment.

Vegetative organs are organs that perform functions related to the individual life of each plant.

In lower plants (algae and yeast), the vegetative body is not divided into organs. Higher plants have such organs; they perform the functions of nutrition and respiration. Thanks to them, the plant exchanges substances with the external environment, reproduces and grows. Plants do not have as many organs as animals, but they can also have different structures and are divided into species.

What plant organs are called vegetative and their types

Vegetative organs include only three parts of the plant - root, stem and leaf. In one plant they are often at different stages of development.

Vegetative organs can be basic, providing nutrition and water supply, and second order.

Plants can reproduce vegetatively. The organs of vegetative propagation of plants are aboveground and underground shoots.

Main vegetative organs of plants

The main vegetative organs include the root and leafy shoots. They perform vital functions for the plant.

The root and its main functions

Each plant has its own type of root.

The root performs the functions:

• fixing the plant in the ground;
• soil nutrition with water and mineral salts in accessible form;
• supply of nutrients;
• reproduction.

The root is an axial organ with radial symmetry. Its tip is covered with a root cap, under which there is educational tissue. Thanks to this tissue, it grows.

All roots are divided into main, lateral and adventitious, and all of them together form the root system. Dicotyledons have tap root systems, with a predominance of the main root. Monocots have fibrous root systems.

Leafy shoots

In the process of evolution, plants adapted to a terrestrial lifestyle due to the appearance of leafy shoots. Later, leaves and roots formed on them.

Escape function is air feeding.

The first shoot grows from the embryonic bud during seed germination. Then it forms side shoots of the second order, and those, branching, in turn, form shoots of the third order, and so on.

Depending on the type of plant, the types of branching are distinguished:

• sympodial is characteristic of many angiosperms and orchids;
• monopodial (palms, phalaenopsis and gymnosperms);
• dichotomous (mosses, ferns).

Depending on the functions they perform, shoots are divided into the following types:

• vegetative;
• generative;
• vegetative-generative.

Shoots bearing flowers are called peduncles.

As a result of the plant’s unusual lifestyle and its adaptation to environmental conditions, modified above-ground shoots appeared. These include: head of cabbage, tendril, spine, aboveground stolon. In some plants, flattened green shoots perform the role of photosynthesis instead of leaves, for example, cladodes in cacti, Decembrists and prickly pear, phyllocladies in butcher's broom, asparagus, phylanthus.

Modified underground shoots have lost the functions of photosynthesis, but they can store nutrients and contribute to the resumption of plant growth and reproduction.

Such escapes include:

• caudex;
• stolon;
• bulb;
• tuber;
• corm;
• rhizome.

The collection of plant tissues that form a shoot is called a meristem. The plant organs located on the shoot or stem (buds and leaves) are connected by a single conductive system.

Autonomic organs of the second order

Stems and leaves are the main parts of the shoot, but are considered as second-order organs. In addition, there are always buds on the shoot.

Leaves

The green color of vegetation on Earth is provided by the pigment chlorophyll, which is found in leaves and ground shoots.

Leaves are the external organs of plants that perform important functions:

• gas exchange;
• moisture evaporation;
• photosynthesis.

In the process of adaptation to growing conditions, the leaves have developed special adaptations.

• Shiny leaves reflect sunlight.
• A waxy coating on the surface of the leaf plate prevents the evaporation of moisture. Pubescence performs the same function.
• Thanks to its rugged leaves, the plant can withstand gusts of wind more easily.
• To protect against herbivores, some leaves, such as those of eucalyptus, produce aromatic oils and poisons.

Modified leaves include:

• trappers - characteristic of carnivorous plants that feed on insects;
• succulent - thick and fleshy leaves that accumulate moisture and nutrients;
• leaf spines are derivatives of the leaf blade (barberry) or spiny stipules (acacia), which protect plants from being eaten by herbivores;
• tendrils - formed from the upper part of the leaves and help the plant cling to the support (peas).

The leaves differ in shape (there are about 30 varieties in total), type of venation, stipule, and type of petiole. According to the division of leaf blades, there are two main forms of leaves - simple and complex, when several leaves are located on one petiole.

Stem

Like the skeleton in humans and animals, the stem in plants serves as a mechanical axis to support the remaining vegetative organs. It also conducts nutrients.

Stems are classified according to various characteristics:

• type of branching;
• location relative to soil level;
• degree of lignification;
• direction and nature of growth;
• cross-sectional shape.

Modified stems can be aboveground or underground. They perform certain functions that are important for the life of plants.

Modified vegetative organs

Only some modified aboveground and underground shoots are listed here. There are also antennae, spines, tuberidia, cladodes and stem-root tuberoids.

Rhizome

Rhizomes are mainly characteristic of herbs.

The leaves on the rhizome are represented by a scaly film, in the axils of which buds grow. Aboveground stems of the plant grow from one part of the buds, and roots from the other. An underground rhizomatous stem grows from the apical bud of the rhizome. The rhizome is resilient; its parts with buds are used for plant propagation.

Stolons

These are thin, elongated shoots with leaf primordia. They are short-lived, unlike rhizomes, but also contribute to the vegetative propagation of plants. In some stolons, the plant accumulates nutrients.

Tubers

An underground organ of a plant.

Tubers form at the top of the stolons. The tuber plant potato is well known to everyone; its tubers accumulate organic substances in the form of starch. On the surface of the tuber there are eyes - small depressions with buds, from which a new potato bush subsequently grows.

Bulbs

Bulbs are also underground shoots that can be spherical, oblong or pear-shaped. The bottom of the bulb is a modified stem, and the scales are leaves. The bulb is characterized by a fibrous root system. New bulbs are formed from the axillary buds - babies.

Kidneys

The role of buds is also great in the vegetative propagation of plants.

A bud is a shoot primordium that forms in the axil of a leaf, at the top of a shoot, root or stem. The buds may be dormant and then they do not open, awaiting the onset of favorable conditions for growth, or a shoot immediately begins to develop from them. Vegetative propagation by above-ground shoots:

1. Some plants are propagated by leaf cuttings, for example, indoor flowers - Crassula, begonia, Saintpaulia.
2. Indoor dracaena successfully takes root using parts of the stem - stem cuttings.
3. Strawberries, wild strawberries and some cereals reproduce by creeping shoots - “whiskers”.
4. Shrubs, such as currants, blackberries, and raspberries, are successfully propagated by layering.

Reproduction by underground shoots:

1. Many herbs, trees and shrubs produce root suckers - these are cherry, lily of the valley, lilac, raspberry.
2. Potatoes and Jerusalem artichokes reproduce by tubers - modified underground shoots.
3. Modified underground shoots also include the rhizome characteristic of lily of the valley, iris, peony and many other plants.
4. Bulbous plants grow from bulbs - modified underground shoots.

The vegetative method of propagation also includes grafting shoots of one species of plant onto the trunk or stem of another.

ROOT

The root is the axial vegetative organ of a plant, which has unlimited apical growth, positive geotropism, has a radial structure and never bears leaves. The apex of the root is protected by the root cap.

The meaning of the root is the anchoring of the plant in the soil, the absorption of water and mineral salts, the storage of organic substances, the synthesis of amino acids and hormones, respiration, symbiosis with fungi and nodule bacteria, vegetative propagation (in root-sprouting plants).

The main root is the root that develops from the embryonic root.

An adventitious root is a root that develops from a stem or leaf.

Lateral root is a branch of the main, lateral or adventitious root.

The main root system is the main root with all the lateral roots and their branches.

Adventitious root system - adventitious roots with all lateral roots and their branches.

Taproot system is a root system with a well-defined taproot.

A fibrous root system is a root system represented mainly by adventitious roots, in which the main root is not distinguished.

Root vegetable is a modified, thickened main root that bears a shortened shoot at the base and performs the function of storing nutrients (carrots).

Root tuber is a modified thickened lateral or adventitious root that performs the function of storing nutrients (dahlia).

Root zones are structures that successively replace each other as the root grows in length.

The division zone is a growth cone, represented by the apical educational tissue, which ensures the growth of the root in length due to continuous cell division.

The elongation zone is the zone of the root where the size of cells increases and their specialization begins.

The suction zone is a zone that moves as it grows, where cells specialize into various tissues and water is absorbed from the soil using root hairs.

The conduction zone is the root zone located above the absorption zone, where water and mineral salts move through the vessels, and carbohydrates through the sieve tubes. The root in this area is covered with cork tissue.

The root cap is a protective, constantly renewing cell formation at the top of the growing root.

STEM

Stem is an axial vegetative organ of a plant, possessing unlimited apical growth, positive heliotropism, radial symmetry, bearing leaves and buds. It connects the two poles of plant nutrition - roots and leaves, brings the leaves to the light, and stores nutrients.

A tree is a life form of a plant with one perennial woody stem - a trunk, on the branches of which (in the crown) there are renewal buds.

A shrub is a life form of a plant with several perennial woody stems bearing renewal buds.

Perennial grass is a life form of a plant that bears one or more non-lignified shoots, the above-ground part of which dies in the fall, and the underground part with renewal buds overwinters.

An annual grass is a life form of a plant whose life cycle continues from seed germination to the formation of its own seeds and death, i.e. one growing season.

The main stem is the stem that develops from the bud of the seed embryo.

The growth cone is a multicellular array of apical educational tissue, which, due to constant cell division, forms all the organs and tissues of the shoot.

A node is a section of the stem from which a leaf emerges.

An internode is a section of a stem between two nodes.

The subcotyledon is the lower portion of the stem between the cotyledon node and the root.

The epicotyledon is the section of the stem between the node of the first true leaf and the cotyledon.

Apical growth - growth of the stem in length due to the work of the growth cone of the apical bud.

Intercalary growth is the growth of the stem in length due to the work of educational tissue at the bases of the internodes.

An erect stem is a stem that grows upward perpendicular to the surface of the earth.

A creeping stem is a stem that spreads along the surface of the soil and takes root with the help of adventitious roots.

Climbing stem – a stem that twines around a support.

A clinging stem is a stem that rises up, clinging to a support with the help of tendrils.

BUD

A bud is a rudimentary, not yet developed shoot, at the top of which there is a growth cone.

Apical bud – a bud located at the top of the stem, due to the development of which the shoot grows in length.

Lateral axillary bud is a bud that appears in the axil of a leaf, from which a lateral branching shoot is formed.

An adventitious bud is a bud formed outside the axil (on a stem, root or leaf) and giving rise to an adventitious (random) shoot.

Leaf bud – a bud consisting of a shortened stem with rudimentary leaves and a growth cone.

A flower bud is a bud represented by a shortened stem with the rudiments of a flower or inflorescence.

Mixed bud – a bud consisting of a shortened stem, rudimentary leaves and flowers.

Renewal bud is an overwintering bud of a perennial plant from which a shoot develops.

A dormant bud is a bud that remains dormant for several growing seasons.

THE ESCAPE

A shoot is a stem with leaves and buds, formed during one summer.

The main shoot is a shoot that develops from the bud of the seed embryo.

Lateral shoot is a shoot that appears from a lateral axillary bud, due to which the stem branches.

An elongated shoot is a shoot with elongated internodes.

A shortened shoot is a shoot with shortened internodes.

A vegetative shoot is a shoot that bears leaves and buds.

A flowering shoot is a shoot that bears reproductive organs - flowers, then fruits and seeds.

INTERNAL STRUCTURE OF THE STEM

The internal structure of the stem of a woody plant is a structure, in a cross section of which the following parts are distinguished: cork, bast, cambium, wood, pith.

Cork is a covering tissue consisting of several layers of dead cells; forms on the surface of wintering stems.

Bast (bark) is a complex of conductive (sieve tubes), mechanical (bast fibers) and main tissues located outward from the cambium; serves to carry carbohydrates from leaves to roots.

The cambial ring is an educational tissue consisting of a single layer of dividing cells; lays bast cells outward, wood cells inward.

Wood is an annually growing complex of conductive (vessels), mechanical (wood fibers) and basic tissues located inward from the cambium; is the support of the stem and serves to conduct water and mineral salts from the roots to the leaves.

The growth ring is a layer of wood formed due to the work of the cambium during one summer.

The pith is the main tissue located in the center of the stem; performs a storage function.

MODIFIED SHOOTS

A modified shoot is a shoot in which the stem, leaves, buds (or all together) irreversibly change shape and function, which is a consequence of adaptive changes during evolution. Similar modifications appear in representatives of different systematic groups of plants, which indicates convergence (homology) under homogeneous environmental conditions.

Rhizome is a modified perennial underground shoot with nodes, internodes, scale-like leaves and buds, serving for vegetative propagation, renewal and storage of nutrients (wheatgrass, horsetail, lily of the valley).

Tuber is a modified underground shoot formed at the top of the stolon, storing nutrients in the thickened stem part and serving for vegetative propagation (potatoes, Jerusalem artichokes). Bears axillary buds.

A stolon is an elongated creeping annual shoot that forms a tuber (potato) at the top.

The bulb is a shortened shoot, the stem part of which is represented by a flat thickening - the bottom. Nutrients are stored in succulent scale-like leaves. The lateral axillary buds, growing, separate. Serves for vegetative propagation and renewal (onion, garlic, tulip).

SHEET

A leaf is a lateral vegetative organ of a plant, growing from the stem, having bilateral symmetry and growing at the base. Serves for photosynthesis, gas exchange and transpiration. Leaf growth is limited.

The leaf base is the part of the leaf that connects the leaf to the stem. Here is the educational tissue that gives growth to the leaf blade and petiole. The base of the leaf sometimes takes the form of a tubular sheath or forms paired stipules.

The leaf blade is an expanded, usually flat part of the leaf that performs the functions of photosynthesis, gas exchange, transpiration and, in some species, vegetative propagation.

Petiole is a narrowed part of a leaf that connects the leaf blade to the base and regulates the position of the leaf in relation to the light source. Leaves with petioles are called petiolate, while those without petioles are called sessile.

Stipules are leaf-shaped structures at the base of the leaf that serve to protect the young leaf and axillary bud.

Leaf axil is the angle between the leaf petiole and the stem, usually occupied by a lateral axillary bud.

Leaf fall is the natural falling of leaves in woody plants and shrubs, associated with the preparation of plants for winter and due to changes in day length. A separating layer is formed at the base of the petiole, due to which the leaf comes off. The cork layer protects the leaf scar.

A simple leaf is a leaf consisting of one leaf blade and one petiole and falling off entirely.

A compound leaf is a leaf that includes several leaf blades (leaflets) located on a common petiole and falling off individually.

Whole leaf - a leaf that has an undivided leaf blade.

Lobed leaf – a leaf whose blade is divided into lobes up to 1/3 of the width of the half-leaf.

A split sheet is a sheet with a plate divided to 1/2 the width of the half sheet.

A dissected leaf is a leaf whose blade is dissected to the main vein or to the base of the leaf.

Leaf veins are a system of conductive bundles that bind the leaf into a single whole, serve as support for the pulp of the leaf and connect it to the stem.

Leaf venation is the order in which the veins are arranged in the leaf blade. With pinnate venation, the main vein is pronounced, from which the lateral veins extend in both directions; with palmate venation, the main vein is not expressed; the leaf includes several large veins, from which the lateral veins extend.

Reticulate venation – venation of the pinnate and palmate types. With parallel venation, several identical veins run parallel to each other along the blade from the base of the leaf to its tip.

Leaf arrangement is the arrangement of leaves on the stem that is most conducive to the performance of their function. With an alternate leaf arrangement, one leaf is attached to each node of the stem; with an opposite leaf arrangement, each node has two leaves opposite each other; with a whorled leaf arrangement, several leaves develop at a stem node.

The edge of the leaf blade is entire, jagged (right corners), serrated (sharp corners), crenate (rounded projections), notched (rounded notches).

INTERNAL STRUCTURE OF LEAF

The outer skin is the covering tissue on the side of the leaf facing the light, often covered with hairs, cuticle, and wax.

The lower skin is the covering tissue on the underside of the leaf, usually bearing stomata.

Stomata is a slit-like opening in the skin of a leaf, surrounded by two guard cells. Serves for gas exchange and transpiration.

Columnar tissue is the main tissue, the cells of which are cylindrical in shape, tightly adjacent to each other and located on the upper side of the leaf (facing the light). Serves for photosynthesis.

Spongy tissue is the main tissue, the cells of which are round in shape, located loosely (many intercellular spaces), closer to the lower skin of the leaf. Serves for photosynthesis, gas exchange and transpiration.

Vein wood is part of the conductive bundle of the leaf, consisting of vessels through which water and minerals flow from the stem to the leaf.

The bast vein is part of the conductive bundle of the leaf, consisting of sieve tubes through which carbohydrates (sugars, glucose) move from the leaf to the stem.

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

The main vegetative organs are the root and shoot (stem with leaves). They provide the processes of nutrition, conduction and dissolved substances, as well as vegetative propagation.

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 division of the plant body into organs and the complication of their structure occurred gradually in the process of development of the plant world. The body of the first land plants - rhinophytes, or psilophytes - was not divided into roots and leaves, but was represented by a system of branching axial organs - telomes. As plants reached land and adapted to life in the air and soil, their 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 revealed. As the plant grows, the size and weight of the body increase, cell division occurs and they 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 detected 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 conductive paths in a polar manner, 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; in this case, a distinction is made between the dorsal (dorsal) and ventral (ventral) sides (for example, leaves, as well as organs that grow horizontally, i.e., having plagiotropic growth). , growing vertically - orthotropic - have radial symmetry.

In connection with the adaptation of the main organs to new specific conditions, a change in their functions occurs, 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 shape 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 ( , which is a reaction to the unilateral action of external factors (light, gravity, humidity). The growth of axial organs towards light is defined as positive (shoots) and negative (main root) phototropism. Oriented growth of axial organs of a plant, caused by the unilateral action of gravity, is defined as geotropism.Positive geotropism of the root causes its directed growth towards the center, negative geotropism of the stem - from the center.

The shoot and root are present in rudimentary form in the embryo located in the mature seed. The embryonic shoot consists of an axis (embryo 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 embryo axis there is a shoot growth point. It is formed by a 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, the leaf primordia grow faster than the stem, with the young leaves covering each other and the growth 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 remaining portion of the embryonic axis, below the cotyledons, is called the hypocotyl, or subcotyledon. Its lower end passes into the embryonic root, which is so far represented only by a growth cone.

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

Almost simultaneously, a first-order shoot, or main shoot, develops from the embryonic bud (apex), which also branches, forming new shoots of the second, third and higher orders, which leads to the formation of the main shoot system.

As for the higher spore shoots (moss mosses, horsetails, ferns), their body (sporophyte) develops from the zygote. The initial stages of the life of the sporophyte take place in the tissues of the growths (gametophytes). An embryo develops from the zygote, consisting of a rudimentary shoot and a root pole.

So, the body of any higher plant consists of shoot and (except for mossy) root systems, built from repeating structures - shoots and roots.

In all organs of a higher plant, three tissue systems - integumentary, conductive and basal - continue continuously from organ to organ, reflecting the integrity of the plant organism. The first system forms the outer protective cover of plants; the second, including phloem and xylem, is immersed in the system of basic tissues. The fundamental difference in the structure of the root, stem and leaf is determined by the different distribution of these systems.

During primary growth, which begins near the tips of the roots and stems, the primary ones are formed, which make up the primary body of the plant. Primary xylem and primary phloem and associated parenchyma tissues form the central cylinder, or stele, of the stem and root of the primary plant body. There are several types of steles.