Venation Meaning, Examples and Relation Between Venation and Roots

Evolution, a key concept in Biology Topics, explains the development of species over time.

What is venation? Give its types

All the leaves contain veins. The arrangement of veins in the leaves of various plants is different. The arrangement of veins in the lamina (or leaf blade) is known as venation of the leaf. There are two main types of venation (or vein arrangements) in the leaves. These are :

1. Reticulate venation, and
2. Parallel venation.

In reticulate venation, the veins in a leaf occur in an irregular way forming a net-like design (see Figure). The term ‘reticulate’ means ‘resembling a net or network’. In reticulate venation, the veins spread out from the mid-rib to all the parts of the leaf haphazardly, giving the appearance of a ‘net’ (or jaal). The examples of plants having reticulate venation in their leaves are : Pea plant, Neem tree, Mango tree, Marigold, Tulsi, Mustard, Sunflower, Orange, Guava, Pulses, Tamarind (Imli), Rose, China Rose, Coriander (Dhania), and Peepal.

In parallel venation, the veins in a leaf run parallel to one another on both the sides of the mid-rib (see Figure). The examples of plants having parallel venation in their leaves are : Wheat, Paddy (Rice), Maize, Millet (Bajra), Sugarcane, Bamboo, Barley, Lily and Banana.

Activity For Taking An Impression Of A Leaf
We can take an impression of a leaf on paper which shows the veins. This can be done as follows : Put a dry leaf of a tree having prominent veins under a white sheet of paper kept on a table [see Figure (a)] Hold the pencil in your hand with its tip sideways and rub it on that part of paper which has leaf below it

[see Figure (a)]. We will get an impression of the leaf on paper having some dark lines on it. These lines show the veins of the leaf [see Figure (b)].

Relationship Between Venation and Type of Roots

We have just studied that there are two types of venation (or arrangement of veins) in leaves : reticulate venation and parallel venation. And we have already studied that there are two types of roots in plants : tap roots and fibrous roots. It has been found by studies that there is a relationship between the type of venation and the type of roots in plants. This relationship is as follows :

1. The plants having leaves with reticulate venation have tap roots.
2. The plants having leaves with parallel venation have fibrous roots.

This means that just by looking at the leaves of a plant, we can tell the type of roots this plant has (even without pulling it out from the ground). This is because if the plant leaves have reticulate venation, then it will have tap root. On the other hand, if the plant leaves have parallel venation, then it will have fibrous roots. For example :

(a) The sunflower plant has reticulate venation in its leaves, so it will have tap root.
(b) The wheat plant has parallel venation in its leaves, so it will have fibrous roots.