Escape of plants: structure and function

The organs of flowering plants, the most evolutionarily developed representatives of this realm of living nature, have a fairly diverse structure and functions. The underground part of the plant is called the root, the above-ground part is the escape. It is the escape of plants that carries out the most important functions: gas exchange, photosynthesis, transpiration, vegetative reproduction and its optimal arrangement with respect to the sun.

Origin of the shoot

In the process of evolution, this organ appears in the first arrivals to the dry land - the rhinophytes. His stems were crooked and forked, as the mechanical tissues were still poorly developed. But even with this primitive structure, the photosynthetic surface increased, which means that the plant organism was better provided with carbohydrates.

What is the escape from plants

Escape the overground part of the plant, consisting of the stem and leaves. All these organs are vegetative, providing growth, nutrition and asexual reproduction.

Escape the plants also contains rudimentary organs - the kidneys. There are two types of kidneys: vegetative and generative. The first species consists of a rudimentary stem and leaf, on top of which there is an educational tissue (meristem), represented by a cone of growth. If in addition to the stem and leaves the kidney contains the rudiments of flowers or inflorescences, it is called generative. In appearance, these buds are distinguished by their larger size and rounded shape.

The place to which the leaf on the stem is attached is called a knot, and the distance between nodes is an interstice. The angle between the stem and the leaf is called the sinus.

In the process of development, the organs responsible for generative (sexual) reproduction appear on the shoot: a flower, a fruit and a seed.

Development of an escape from the kidney

With the onset of favorable conditions in the spring, the meristem cells of the cone of growth begin to actively divide. The shortened internodes increase in size, resulting in a young shoot of plants. At the very tip of the stem are the apical buds. They provide the growth of the plant in length. The axillary and accessory buds are located in the leaf axillary or internodes, respectively. Due to them the stem forms lateral shoots, that is, branches.

Methods of branching plants

Depending on the structure, there are several ways to branch shoots:

1. Dichotomous . The most primitive type of branching, in which two develop from one growth point, two from each of them, etc. So grow some algae and higher spore plants: the plains and ferns.
2. Primopodial . This branching can be seen both in gymnosperms (pine, spruce), and angiosperms (oak, maple). For a long time, the stem of these plants grew in length with subsequent lateral branching.
3. Simpodial. In this way, apical growth, on the contrary, is suspended. And lateral buds actively grow, forming more and more lateral shoots. Pear, cherry and other flowering plants are a typical example of this type of growth.

Modifications of shoots

What is the escape from plants and how it looks, of course, everyone knows. But environmental conditions often require the appearance of additional functions. This is easily provided by the organs of flowering plants. Escape is modified, acquiring new features of the structure, while it consists of parts of the standard escape.

The main modifications of the escape include:

• Rhizome - is under the ground, where it most often grows horizontally. It has elongated interstices and kidneys, from which leaves appear on the surface of the earth in a favorable period. Therefore, it is very difficult to get rid of plants that have rhizomes (lily of the valley, wheatgrass, valerian). After tearing off the leaves, the shoot itself remains in the ground, growing larger and larger.

• Tuber - thickened internodes, with kidneys - eyes. The brightest representative of the plants forming the tubers is the potato. Since it grows in the earth, it is often confused with a modified root. However, there are aboveground tubers, for example, in kohlrabi.
• Bulb - a modified shoot of plants with well-developed leaves, located on a flat stem - the bottom. Characteristic for garlic, onion, tulip, lily. The internal juicy leaves accumulate nutrients, and the outer dry leaves protect them from damage.
• Spines are a protective device for pears, sea buckthorn, hawthorn and other plants. Being in the axillary leaf, they reliably protect the plant from animals that want to eat them.
• Antennae - modified twisted shoots, fixing plants in a certain position. Cucumber, grapes, pumpkin are the most common plants using this device.

• Mustache - thin shoots with long internodes. Strawberries and strawberries vegetatively reproduce with the help of a mustache.

As you can see, the escape of plants consists of parts that are functionally interconnected, can be modified depending on environmental conditions and give each plant its own unique appearance.