What is an escape? The structure of the escape

The aerial part of plants is called the "escape". Its structure is due to the functions performed. Of course, each body is indispensable and determines the possibility of the existence of a biological species. Nutrition functions, growth processes, the possibility of adaptation are just some of the most important functions of the visible part of plant organisms.

Biology: the structure of escape

In morphology, the axial and lateral parts of this organ are distinguished: stem and leaf. The structure of the shoot of the plant is striking in its variety: from microscopic water duckweed to giant forest sequoia. It is due to the different structure of the components of the aboveground part, connected with the features of the habitat and climatic conditions. Here, too, are shortened rudimentary shoots - the kidneys.

The place of attachment of the sheet to the axial part is called the knot, and the angle that forms between them is the sinus. Here are specialized kidneys, forming leaves or flowers. The distance between the two places of attachment of the leaves is called interstitial.

Stem

The structure of the shoot initially depends on the direction of growth and location in the space of the stem. Depending on these characteristics, stand upright, creeping, creeping, climbing and clinging species are distinguished. Varied stems and the nature of the surface. It can be naked or with outgrowth, smooth or rough. If you cut the stem across, you can determine the shape: rounded, ribbed, with a certain number of faces or oblate.

The mustache of strawberry is also its escape, having shortened internodes.

Depending on the life form, there are herbaceous and woody stems. The first do not have a cambium - a lateral educational tissue. In the first years of life, outwardly new shoots of trees and shrubs look like them. They are green and capable of photosynthesis. Over time, they become lighter, becoming more durable. They are able to hold large fruits and withstand strong wind gusts.

Types of stems

Depending on the features of the development cycle, plants can be single, bi-annual and perennial. For example, asters fade in autumn, after which they die completely. Carrot and beet grow differently. In the first year of life, they form root crops, which are organs that store nutrients. In the autumn, their stem dies. But the plant exists in the form of a modified stem. With the advent of favorable conditions, the escape again grows. At the same time for the second year of life on it as a result of flowering, seeds are formed, through which the plant multiplies.

The cycle of life of perennial plants will be examined by studying the features of the structure of shoots of coniferous plants. These are shrubs or trees with a single powerful stem - the trunk. Its development begins with the germination of the seed. As a result of its growth, a seedling is formed, and then an adult plant. The life cycle of perennial plants ends with death. Conifers are rightly considered to be real long-livers. So, the pine lives about 400 years, spruce - up to 500, and juniper - as many as 1000!

Sheet

The lateral part of the shoot is no less functional and diverse. It provides air supply, transpiration - evaporation of water from the surface, vegetative reproduction. Escape, the structure of which is determined by the functions performed, is characterized by a variety of leaves.

Cactus needles are needed to reduce the amount of moisture evaporated. A thumbnail wide at the horse chestnut, on the contrary, increases its number.

Leaves with a single plate are called simple, and with a few located on one stalk, they are complex. Considering them, you can see a certain pattern. It creates veins. These are vascular fibrous bundles of conductive tissue. According to the nature of venation, the leaves are distinguished from mesh (maple, apple), parallel (corn, rye) and arched (plantain, lily of the valley) venation.

Sheet Layout

Escape, whose structure depends on the amount of solar energy received, is characterized by a different arrangement of leaves on the stem. In the case of their location, a regular spiral forms, and if the circle is opposite, or whorled.

In nature, there are no plants that do not renew foliage. She is thrown off both pine and spruce. Since not all the leaves fall off at once, no one notices this.

Modifications of escape

When there is a need to perform additional functions, shoots and their constituent parts are modified. Leaves can turn into spines or scales. In plant predators they are able to trap and digest small insects.

Features of the structure of the shoot can be considered and the example of the bulb. Its flat modified stem is called the "bottom". There are several kinds of leaves on it: juicy - for storing water and nutrients, dry ones - for protection. In addition, from the kidneys, in the presence of a sufficient amount of water, young green leaves grow. The stalk root system also grows from the stem .

The tubers of Jerusalem artichoke, also called an earthen pear, also form a modification of the shoot - the tuber. On the thickened fleshy stem there are scarring kidneys, from which young shoots grow.

Underground stems with elongated interstices are rhizomes. They are like whips, they have well-developed mechanical and conductive tissues. Of the kidneys located on the rhizome, leaves are formed. Those who are new to the peculiarities of the structure of the rhizomes, believe that if you get rid of the leaves, the whole plant will die. But this opinion is erroneous, because the main part of the plant is reliably protected and is underground.

Interrelation of structure and functions

The structure of the escape depends on the functions performed. This can be proved by considering the elements of the structure of its parts. The sheet is covered on the outside with a living tissue skin, in which are holes - stomata. They are necessary for protection and gas exchange. The internal content of the leaf is represented by the main storing and chlorophyll-bearing tissue, which is responsible for autotrophic nutrition of the whole plant. Elements of conductive and mechanical tissue, forming veins, are the basis for transporting the entire gamut of essential nutrients.

The vegetative organs of the plant are the root (its underground part) and escape. The structure of generative parts does not allow them to perform such functions. They carry out the process of sexual reproduction and spread of plants. But the flower develops on the stem, and for its development organic substances, formed in the leaves, are needed.

It can be concluded that the plant is a single organism, the functioning of parts of which is interrelated.