Modified plant shoots

The shoots of plants amaze with their diversity and uniqueness. But environmental conditions often require representatives of this kingdom to have new adaptations. Modified shoots are able to perform additional functions. Thus, they provide a higher viability of organisms.

Modifications of underground shoots

These metamorphoses can be above the ground or underground. Modified subterranean shoots are the most common and widely represented in nature.

One of them is the rhizome. Both the name and appearance look like a root. But, unlike an underground organ, it consists of elongated interstices and nodes. On the stem of the rhizome are subordinate buds, from which, with the advent of favorable conditions, leaves grow. In the nodes there are also additional roots. The elongated horizontal stem is located under the ground, where temperature changes and drought less affect the vital activity of the plant. And the supply of water and nutrients significantly increases the chances of the plant organism to survive.

Many faced the situation when it is necessary to get rid of bored wheatgrass, strongly overgrown lilies of the valley or other plants that have a rhizome. It is not so easy to do this. Modified shoots are greatly expanded, their parts often remain in the ground, forming new shoots. But, on the other hand, this ability is often used for vegetative propagation of plants.

Tuber

Tuber - a modified shoot, which is also underground and stores nutrients. Everyone knows potato tubers, which are of great economic importance. They accumulate a large amount of starch.

Some mistakenly consider this modified shoot as a fruit. In fact, the fruits of potatoes are formed on the above-ground shoots after flowering. Tuber is a thickened stem with apical and lateral kidneys - eyes. Sprouting, eyes form young shoots.

Long elongated and short-lived shoots are also called stolons.

Plants such as saffron and gladiolus have a corms - a thickened stem with subordinate roots. Protects the inner contents of the corms layer of dead leaves.

Bulb

Onion, garlic, tulip and lily have a different modification - an onion. On the flat stem, which is called the Don, there are kidneys. Of these, several species of scaly leaves develop. Some of them are thick and fleshy. They store water with nutrients, providing life to the plant. They are protected from above by dry, leafy leaves. From sleeping buds on the bottom of the growing young leaves of onions, the so-called green onions. Bulbs are also characteristic of plants of the steppe natural zone. In the conditions of a cold little snowy winter and a hot dry summer, this modification gives the plant the opportunity to survive an unfavorable period under this ground.

Aboveground modifications of shoots

Modified plant shoots can also be located above the ground. So, on the branches of hawthorn and thorn are thorns - shortened and lignified modified shoots. They represent the result of branching and sharpening of the stem, reliably protecting their owners from eating animals. Plants with spines have tasty, juicy fruits with a bright color, so they need additional protection.

Strawberries and strawberries have an additional device for vegetative reproduction - elongated shoots of a mustache. They are fixed in the soil, forming a new plant.

The mustache must not be confused with the antennae of the grapes. They have a completely different functional purpose. With the help of antennae, the plant is attached to the support, occupying the most favorable position in relation to the sun. This device is also characteristic for pumpkin, cucumber, watermelon.

Modifications of shoots in the direction of growth

Depending on the conditions of growth, shoots can also be modified. In woody and herbaceous plants, erect stems directed toward the sun are most often encountered. Creeping and creeping stems grow very quickly, cover the surface of the soil with shoots with leaves. This provides them with a prosperous existence. Plants with frizzy stems are called lianas. They are typical for tropical and moist equatorial forests, although they are often found in the temperate zone. For attachment to the support of the creeper, special devices are used: hooks, hooks, bristles.

Internal structure of escapes

Despite the external differences, various modifications retain all the features of the internal structure. For example, the potato tuber, being a thickened stem, is covered with bark from above. It is we who clean it when we clean potatoes. On the longitudinal section of the tuber, the dark stripe - the wood - is clearly visible. And in the core, loose basic tissue, spare nutrients are actively deposited.

If the potato tubers are left in the open for a long time, they will start to turn green. This indicates that the colorless plastids of leukoplasts, in which starch accumulates, are converted into green plastids by chloroplasts. Such a product can not be eaten, since it contains a poisonous alkaloid solanine, which is poisonous to the body.

Functions of the modified shoots

It is the modified shoots that determine the survival of plants under adverse conditions. By storing valuable nutrients, they allow the plants to survive during the drought period. Biennial and perennial plants survive only due to the presence of bulbs and rhizomes. Their leaves, which appear on the surface in spring and develop all summer, with the onset of cold autumn die. And the underground part lives on the supply of thickened stems. With the onset of heat, the plant again resumes growth.

Many modifications of the shoot serve for vegetative reproduction, increasing the number of valuable plants quite quickly. This property is actively used by man in agriculture.

Origin of the flower

A flower is a modified escape. Prove this fact is very simple. It develops from a specialized generative kidney. Characteristic features this part of the shoot acquires for the fulfillment of the most important additional function - the implementation of sexual reproduction of plants. For this, you need a flower. The modified shoot is considerably shortened in comparison with ordinary stems. Its main parts are the stamen and pestle, in which are the sex cells - the sperm and the egg, respectively. The bright color of petals of a flower is needed to attract pollinating insects. Small flowers are collected in groups - inflorescences. So they are much more noticeable, and their aroma is spreading more.

After pollination and fertilization in place of the flower, a fetus is formed. It consists of seeds and pericarp. Seeds give rise to a new plant, and the pericarp harbors and warms them.

In addition, the flower is a modified escape, which for many centuries has brought aesthetic pleasure to people, inspiring poets and musicians.

Modified shoots are one of the main adaptations of higher plants to environmental conditions. In the process of evolution, they appeared to increase the viability of plant organisms in connection with the need for the emergence of new functions in the ever-changing conditions of life.