Each part of the plant performs its main functions based on the characteristics of its structure. But the modification of the leaves, as well as other necessary organs, allows them to acquire additional ones. Most often they depend on the climate and growing conditions.
Tropical leaf modification
Plants of humid equatorial forests are very easy to recognize - by the characteristic shape and size of their leaf blades. In the tropical climatic zone, their tree forms occupy a dominant position, giving life only to shade-tolerant shrubs and grasses. The leaf blades of such plants are unusually large and wide. How to explain such a structure? The thing is that one of the functions of this part is the implementation of transpiration. This is the process of evaporation of water from the surface of the leaf. The larger the area of the plate, the more intense the gas exchange with the environment. And in conditions of high humidity, this is simply necessary to prevent rotting processes.
Thorns
Thorns are also modifications of plant leaves. They are characteristic of those that grow in arid anddesert conditions. Everyone has seen cactus thorns. These are its leaves. In conditions of lack of moisture, when the transpiration process must be minimized, this is an ideal adaptation. With such a small surface of the leaf blade and water, very little will evaporate.
However, the thorns of cactus and acacia are a different modification of the leaves. What's the Difference? In white acacia, hawthorn, blackthorn, barberry and other similar plants, the spines are modified stipules, and not the plates themselves. Their main function is to protect fragrant flowers and sweet fruits from being eaten by various animals.
Needles
The needles of all representatives of the department of gymnosperms are also a modification of the leaves. Everyone remembers the children's riddle about the Christmas tree - "in winter and summer in one color." And all conifers are evergreen in many respects precisely due to the characteristic modifications of the leaves. In cross section, they have a rounded or ribbed shape. Such leaves have a small area, like the spines of cacti. Their stomata, through which gas exchange occurs, are immersed in the integumentary and main part of the leaf. This reduces the rate of water evaporation. In the winter season, these formations are completely sealed with wax, which reduces transpiration to almost zero. Therefore, at a time when all angiosperms shed their leaves for the winter, conifers and shrubs can boast of lush green decoration.
Desert plant leaves
It is not easy for plants to survive in arid conditions. What causes the modification of leaves in these plants? They need to have such structural features that will allow them to survive with sudden changes in temperature and lack of moisture. Therefore, their leaves are often covered with a thick layer of hairs, or a wax coating. They protect plants from excessive moisture loss. There is another device as well. Many types of arid ecosystems store water in thick, fleshy leaves. An example of such a modification is aloe, which is often bred as a houseplant with healing properties.
Antennae
To consider the features of the following organs, let's recall what leaf modifications are found in the legume family. The shoots of most of them are long and thin, and the fruits, when ripe, acquire a mass that does not allow them to stay upright. But it is the most beneficial for the productive implementation of photosynthesis. What leaf modifications are found in peas? Of course, these are mustaches. This is how individual plates from a complex sheet are modified. With their help, the plant clings to the support, and as a result, a weak and thin stem is located in the required position.
Scales
To understand why bud scales are a modification of a leaf, it is necessary to understand the structure of the bulb. Consider it on the example of a common leek. Its bulb, despite being underground, is a modificationthe above-ground part of the plant - the shoot. This is easy to prove. The shoot consists of a stem, leaves and buds. The same parts are in the bulb. Its flat stem is called the bottom. A bundle of adventitious roots departs from it. Above are several types of leaves. Young ones are green and grow from buds located on the bottom. Juicy and fleshy leaves take on this form in order to store moisture. With its help, the plants in which the bulb is formed endure drought, low temperatures and other adverse phenomena underground. And dry scales, which are also a modification of the leaves, protect the internal contents of the bulb from mechanical damage.
Predatory leaves
Modifying leaves can also be very dangerous for other living beings. There is a whole group of insectivorous plants. They are also capable of carrying out the process of photosynthesis, that is, they are autotrophs. But if there are no conditions for its occurrence, then they switch to a heterotrophic mode of nutrition. With the help of modified leaves, they catch insects and digest them. For example, in the tropical plant sarracenia, the leaves are funnel-shaped, bordering fragrant nectaries. They also attract insects. Approaching, the victim begins to slide along the edges of the funnel and is trapped. In addition, the leaves also secrete special narcotic substances that immobilize insects of any size. On top of the funnel, the sheet is twisted in the form of a hood. This fold prevents rain from getting inside, mixing with digestiveenzymes.
Mobile sundew tentacles, at the ends of which there is a sticky liquid, also belong to the modifications of the leaves. It attracts insects that land to feast and become trapped.
Leaf buds
All leaves are vegetative organs. With their help, the process of asexual reproduction is carried out. For example, if you separate a leaf of an uzambar violet from an adult plant and place it in a container of water, after a while it forms a root. But in a number of plants, the process of reproduction occurs differently. So, at the room Kalanchoe, along the edge of the leaf blade, there are buds, from which young shoots develop independently. They are almost fully formed: they have a small root and leaves. Falling off, they germinate in the same container as an adult plant. This process is also called self-propagation.
The significance of plant leaf modifications is great. These adaptations increase vitality and facilitate the process of adaptation. Thanks to the modifications of the leaves, land plants were able to master various climatic zones, differing in the level of moisture, temperature and soil properties. In addition to photosynthesis, transpiration and cellular respiration, leaf modifications allow them to perform other important functions: protection from predators and mechanical damage, regulation of gas exchange and the level of water evaporation, and heterotrophic nutrition.
