Venation of leaves: types, structure, examples

The leaf is an aerial part of plants and provides performance of a number of the most important functions. One of them is the realization of an ascending and descending current of water with nutrients dissolved in it. This largely occurs with the help of fibrous vascular bundles - veins. They are easily seen on the leaf blade even with the naked eye. Venation of leaves, its types and features of functioning and will be considered in our article.

What is leaf vein

For sure, considering the leaf blade, you noticed intricate patterns on its surface. This is the veins of the leaves. But this is not just a characteristic drawing. It is an element of the conductive tissue of plants. The veins, which are also called vascular fibrous bundles, consist of vessels and sieve tubes. The first provide an upward flow of water. Its essence lies in the movement of the liquid with the minerals dissolved in it from the root to the leaves. This process is very important, because for the process of photosynthesis water is a necessary condition.

Venation of leaves provides the reverse process. Its essence lies in the movement of organic substances that were formed in the leaf during photosynthesis, to other parts of the plant. This is done by the sieve tubes of the conducting tissue. As a rule, the vessels are located above the sieve tubes and together form the so-called core sheet.

Types of leaf venation

Vascular fibrous bundles are arranged in leaves in different ways. The nature of their location - this is the venation of the leaves. This feature is systematic. This means that by its type it is possible to determine the classification unit of the plant. For example, reticular venation is characteristic of leaves of dicotyledonous plants. Such a pattern has leaves of cherries, pears, apples. A parallel and arc - for monocots. Examples of plants with this type of venation are lily of the valley, leek, wheat, barley. The nature of venation is easy to determine visually. Let's take a closer look at its main types.

Parallel venation of leaves

There is a clear relationship between the type of leaf blade and venation. Consider this for the example of wheat grass. This plant with linear leaves is a malignant weed. Getting rid of it can be difficult. The veins on such leaves really are located almost in one line. This type of venation is called parallel. It is characteristic of all cereals, which are representatives of monocots.

Arc vein

If the leaf blade is wider, but elongated, the veins come out of its base. Further they diverge in the form of arcs, but are joined at the top. The main vein among them can not be distinguished, since they are all of the same shape and size. This arched venation of leaves, which is typical for plantain, lily of the valley, tulip.

Mesh threading

This type of venation is most often found in nature. This fact is easy to explain. Mesh venation of leaves is characteristic of the green part of all bipartite representatives, and they occupy a dominant position in the plant world. In terms of abundance and species diversity, they significantly exceed all others.

Everyone saw leaves of maple or apple. They clearly stand out the main vein. From it, less noticeable vascular fibrous fascicles of the second order extend in both directions. In relation to each other, they are located almost parallel. From veins of the second order, in turn, even smaller ones depart. Together they form a dense network of elements of the conductive tissue of the leaf blade. To effectively provide all the substances necessary for life, this is the most perfect type of venation. Plants families Rosaceae, Cabbage, Legumes, Nightshade, Astrological are a prime example.

So, let's sum up: the venation of the leaves is the character of the location of vascular fibrous bundles on the plate. They are elements of the conductive tissue and ensure the movement of nutrients through the plant. There are three main types of venation: mesh, parallel and arc.