Question

How many types of leaf venation are there?

Answer 1

Hint: Leaf venation is described as the arrangement of veins in the lamina of a leaf. The veins are composed of vascular tissues that are very essential for the transport of food and water. There are two main vascular tissues in leaf veins named xylem and phloem. Xylem is important for the transport of water and soluble ions into the leaf, and phloem is vital for the transport of carbohydrates which are made by photosynthesis from the leaf to the rest of the plant.

Complete step-by-step answer:
1) Parallel venation: In this type of venation, the veins of the leaf run parallel to each other. This type of venation mainly occurs in monocot plants. The presence of mid veins classifies parallel venation into two categories: -
- Pinnate/Unicostate parallel venation - In this venation, veins emerge from an evident midvein found in the center of the leaf lamina from the base to the apex, where veins develop perpendicular to the mid vein towards the margin and are parallel to each other. E.g., banana
- Palmate/Multicostate parallel venation: In this type of venation, several prominent veins run parallel to each other. It in turn can be of two types—divergent or convergent parallel venation. e.g., Borassus (Divergent) and grass (Convergent).
2) Reticulate venation: In this type of venation, veins are arranged in the form of a network, arising from the mid-vein. Such types of venation mainly occur in Dicot plants. It can be classified into two types:-
- Pinnate/Unicostate reticulate venation—A single mid-vein is present in this venation, and all other veins form a web-like structure. Mangifera leaves
- Palmate/Multicostate reticulate venation-In this type of venation, midribs are found, and other veins form a network. The venation is of two types: divergent and convergent reticulate venation.
     

   Image - Parallel venation

     

Image - Reticulate venation

Note:Unicostate: This defines having only one costa or rib i.e. having one primary or prominent rib, the midrib.
 Multicostate: This type of leaf venation is defined as having several costate or ribs.