Without plants it is impossible to imagine terrestrial landscapes. They play an important role in the ecosystem of the planet, maintaining the necessary oxygen content in the air and creating a fertile soil layer. The vegetative organs of plants help them to perform basic vital functions and interact with the environment.
Material Content:
Vegetative organs of plants - what is it?
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 environment, multiplies and grows. Plants do not have as many organs as animals, but they can also have a different structure and are divided into species.
What plant organs are called vegetative and their types
Only three parts of the plant are referred to vegetative organs - the root, stem and leaf. In one plant, they are often at different stages of development.
Plants can reproduce vegetatively. The organs of the vegetative propagation of plants are above-ground and underground shoots.
The main vegetative organs of plants
The main vegetative organs include root and leafy shoots. They perform vital functions for the plant.
The root and its main functions
The root performs the functions:
- fixing the plant in the ground;
- soil nutrition with water and mineral salts in an accessible form;
- supply of nutrients;
- reproduction.
The root is an axial organ with radial symmetry. Its tip is covered with a root case under which the educational tissue is located. Thanks to this fabric, it grows.
All roots are divided into main, lateral and subordinate, and all of them together form the root system. In dicotyledons, the root systems are pivotal, with a predominance of the main root. In monocotyledonous plants, the root systems are fibrous.
Leafy shoots
In the process of evolution, plants have adapted to the terrestrial way of life due to the appearance of leafy shoots. Later, leaves and roots formed on them.
The first shoot grows from the germinal bud during seed germination. Then it forms lateral 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, branching types are distinguished:
- sympodial is characteristic of many angiosperms and orchids;
- monopodial (palms, phalaenopsis and gymnosperms);
- dichotomous (mosses, ferns).
Depending on the functions performed, the shoots are divided into the following types:
- vegetative;
- generative;
- vegetative-generative.
Shoots that carry flowers are called flower stalks.
As a result of the plant’s unusual lifestyle and its adaptation to environmental conditions, modified aerial shoots appeared. These include: head of cabbage, antennae, prickle, elevated stolon. In some plants, flattened green shoots play the role of photosynthesis instead of leaves, for example, cladody in cacti, Decembrists and prickly pear, phyllocladia in needles, asparagus, and philanthus.
Modified underground shoots have lost the function of photosynthesis, but they can store nutrients, contribute to the resumption of growth and reproduction of plants.
These shoots include:
- caudex;
- stolon;
- bulb;
- tuber;
- corm;
- rhizome.
The collection of plant tissues that make up the shoot is called the meristem. Plant organs located on the shoot or stem (buds and leaves) are connected by a single conductive system.
Vegetative organs of the second order
Stems and leaves are the main parts of the shoot, but are considered as organs of the second order. In addition, there are always kidneys on the shoot.
Leaves
Leaves are the external organs of plants that perform important functions:
- gas exchange;
- moisture evaporation;
- photosynthesis.
In the process of adaptation to the growing conditions, special adaptations were formed in the leaves.
- Shiny leaves reflect sunlight.
- Wax coating on the surface of the sheet plate prevents the evaporation of moisture. Pubescence performs the same function.
- Thanks to the rugged leaves, the plant tolerates wind gusts more easily.
- To protect against herbivores, some leaves, for example, in eucalyptus, produce aromatic oils and poisons.
To modified leaves include:
- hunting - characteristic of predatory plants that feed on insects;
- succulent - thick and fleshy leaves that accumulate a supply of moisture and nutrients;
- leaf spines are derivatives of the leaf blade (barberry) or prickly stipules (acacia) that protect plants from being eaten by herbivores;
- antennae - formed from the top 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, stipulation, type of petiole. According to the separation of leaf plates, there are two main forms of leaves - simple and complex, when several leaflets are located on one petiole.
Stem
Stems are classified according to various characteristics:
- type of branching;
- location relative to soil level;
- degree of lumbering;
- direction and nature of growth;
- cross-sectional shape.
Modified stems can be aboveground and underground. They perform certain functions that are important for plant life.
Modified Vegetative Organs
Only some modified aboveground and underground shoots are listed here. There are also antennae, thorns, tuberidia, cladodes and stem-root tuberoids.
Rhizome
The leaves on the rhizome are represented by a scaly film, in the sinuses of which buds grow. Elevated stems of the plant grow from one part of the buds, and roots from the other. An underground rhizome stem grows from the apical kidney of the rhizome. Rhizome is viable; its parts with buds are used for plant propagation.
Stolons
These are thin, elongated shoots with buds of leaves. They are short-lived, unlike rhizomes, but also contribute to the vegetative propagation of plants. In some stolons, a plant stores nutrients.
Tubers
Tubers form at the top of the stolons. Potato is a well-known tuber plant, in the tubers of which organic matter in the form of starch accumulates. On the surface of the tuber there are eyes - small indentations with buds, from which a new potato bush subsequently grows.
Bulbs
Bulbs are also underground shoots, which can be spherical, oblong or pear-shaped. The bottom of the bulb is a modified stem, and the scales are leaves. The bulbous root system is characteristic of the bulb. From the axillary kidneys, new bulbs are formed - children.
Kidney
A bud is the germ of an shoot that forms in the bosom of the leaf, on top of the shoot, root or stem. The buds may be dormant and then they do not open, waiting for the onset of favorable conditions for growth, or from them an shoot immediately begins to develop.
The kidneys are also divided:
- by functions (floral, leafy, mixed);
- by structure (bare and protected);
- and by location (alternating, opposite, whorled, apical).
Vegetative method of plant propagation
Vegetative propagation by aerial shoots:
- Some plants propagate by leafy cuttings, for example, indoor flowers - Crassula, begonia, Saintpaulia.
- Indoor dracaena is successfully rooted in parts of the stem - stem cuttings.
- Strawberries, strawberries and some cereals propagate by creeping shoots - "mustache".
- Shrubs, such as currants, blackberries, raspberries, successfully propagated by layering.
Propagation by underground shoots:
- Many herbs, trees and shrubs give root offspring - this is cherry, lily of the valley, lilac, raspberry.
- Potatoes and Jerusalem artichoke are propagated by tubers - modified underground shoots.
- Modified underground shoots also include a rhizome characteristic of lily of the valley, iris, peony and many other plants.
- Bulb plants grow from bulbs - modified underground shoots.
The vegetative method of propagation also includes the grafting of shoots of a plant of one species onto the trunk or stem of another.
