Question

_______ is an example of a pinnate type of venation of leaf blade.
A) Cosmos
B) Castor
C) Tapioca
D) Semul

Answer 1

Hint: Venation is the pattern of arrangement of veins in the leaves of plants. These veins consist of vascular tissues (xylem and phloem).

Complete answer:
1.Pinnate or unicostate venation: In this type, the leaf has one main vein placed at the center of the leaf which is called the midrib. Other veins arise from the main vein. They are called lateral veins. Example: Cosmos.

2. Palmate or multicostate venation: In this type, there are many veins arising from the same base but flaring out in different directions. These veins also give rise to other small veins (lateral veins). Example: Castor.

There is another type of venation too that is Reticulate and Parallel type of venation.
Reticulate venation: In this type of venation leaf contains a midrib from which several secondary veins arise that branch like a network. In this, veins form a network-like structure throughout the leaf. This is found in mango leaves. This type of venation is found in Dicots.
Pinnately reticulate venation (unicostate): In this, there is one midrib in the center from which many lateral branches arise to form a network, Example: Mangifera indica.
Palmately reticulate venation (multicostate): In this, there are two or more principal veins arising from a single point and they proceed outwards or upwards, Example: Cucurbita.

Parallel venation: In this, all veins are parallel to each other. This is found in banana leaves. This type of venation is present in monocots.

Hence, the correct answer is option (A)

Note: Pinnately Parallel Venation (Unicostate): In this, there is a prominent midrib in the center, from which arise many veins perpendicularly and run parallel to each other, Example: canna.
Palmate Parallel Venation (Multicostate): In this, several veins arise from the tip of the petiole and they all run parallel to each other and unite at the apex, Example: Rice, bamboo.