Question

In a leaf with parallel venation

(a) Veins form network on the leaf

(b) Veins run parallel to the midrib

(c) Veins rum horizontal to the midrib

(d) Veins criss cross each other to form an irregular pattern

Answer 1

Arrangement of veins in a leaf is called venation. In a leaf, two types of venation are found: Reticulate venation and parallel venation. In parallel venation, the veins run parallel to the midrib over the leaf blade or lamina. All monocots exhibit parallel venation. Ex: Banana, Bamboo, wheat etc.

Complete answer: Arrangement of veins in a leaf is called venation. Veins are part of the conducting system of a plant (vascular tissues), arising from stem to leaf. The venation in a leaf is broadly divided into two types: Reticulate venation and parallel venation.

When the veins form a network or web-like pattern on the leaf, it is called reticulate venation. Dicotyledons are examples of reticulate venation. Ex: Mango, Hibiscus etc.

However, when veins run parallel to the midrib over the lamina, it is called parallel venation. This type of venation is a characteristic feature of monocots. Ex: Wheat, maize, grass, bamboo, banana etc.

So the correct answer is (b) Veins run parallel to the midrib

Parallel venation can further be divided according to the following:

1. Unicosate or pinnate venation: Single prominent veins give rise to several lateral veins, which run parallel to each other.

Ex: Banana, Canna etc

2. Multicostate or Palmate venation: Several prominent veins run parallel to each other. It is again of two types: Convergent parallel and Divergent parallel

Note: Although parallel venation is the characteristic feature of monocot plants, exceptionally, there are few dicots plants such as Calophyllum and Eryngium which show parallel venation