The leaf is the above-ground part of plants and provides a number of important functions. One of them is the implementation of an upward and downward flow of water with nutrients dissolved in it. This largely occurs with the help of vascular fibrous bundles - veins. They are easy to see on the leaf blade even with the naked eye. Leaf venation, its types and features of functioning will be discussed in our article.
What are leaf veins
Surely, 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 pattern. 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 a liquid with minerals dissolved in it fromroots to leaves. This process is very important, because water is a necessary condition for the implementation of the process of photosynthesis.
Vination of leaves also 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 sieve tubes of conductive tissue. As a rule, the vessels are located above the sieve tubes and together form the so-called core of the leaf.
Types of leaf venation
Vascular fibrous bundles are located in the leaves in different ways. The nature of their location 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, reticulate venation is characteristic of the leaves of dicotyledonous plants. The leaves of cherries, pears, apples have such a pattern. And 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 lamina type and venation. Let's take a look at the wheatgrass as an example. This linear-leaved plant is a noxious weed. Getting rid of it can be quite difficult. The veins on such leaves are really located almost in one line. This type of venation is calledparallel. It is characteristic of all cereals, which are representatives of monocots.
Arc venation
If the leaf blade is wider, but elongated, then the veins come out of its base. Further, they diverge in the form of arcs, and connect at the top. It is impossible to single out the main vein among them, since they are all the same shape and size. This is the arc venation of the leaves, which is typical for plantain, lily of the valley, tulip.
Reticulate venation
This type of venation is the most common in nature. This fact is easy to explain. Reticulate venation of leaves is characteristic of the green part of all dicotyledonous representatives, and they occupy a dominant position in the plant world. In terms of abundance and species diversity, they significantly exceed all others.
Everyone has seen maple or apple leaves. The main vein is clearly distinguished on them. Less noticeable vascular-fibrous bundles of the second order depart from it in both directions. In relation to each other, they are located almost parallel. From the veins of the second order, in turn, depart even smaller ones. 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 of the families Rosaceae, Cabbage, Legumes, Solanaceae, Asteraceae are a prime example.
So, to summarize: leaf venation isthe nature of the location of the vascular fibrous bundles on the plate. They are elements of a conductive tissue and ensure the movement of nutrients throughout the plant. There are three main types of venation: reticulate, parallel and arcuate.
