Question

Cotton and Madar (Calotropis) seeds are dispersed by air as they have
A. Pappus
B. Wings
C. Hair
D. Flattened surface

Answer 1

Hint: Seed dispersal is the movement or transport of seeds away from the parent plant and this mechanism is present in all seed bearing plants. Plants are not so mobile and depend upon a variety of dispersal mechanisms to transport their seeds.

Complete answer:
Seed dispersal is a very important mechanism for the plants and has several benefits for different plant species. Seed dispersal mechanism includes both abiotic vectors such as wind, water and biotic vectors like birds.
Seed dispersal is of four types:
Dispersal by water: In this seeds develop floating ability in the form of spongy outer coat (coconut).
Dispersal by wind: In this seeds develop hairs, wings and papus for dispersal.
Dispersal by animals: In this seeds develop hooks by which they get attached to the bodies of animals (xanthium).
Dispersal by bursting/gravity: In this fruit burst with the full force and seeds are dispersed in the environment (apple and okra).
Seed dispersal by wind is also known as Anemochory. In this dispersal mechanism seeds have feathery pappus (dandelions), wings (physalis) and flattened surface which helps them to float easily. Seeds dispersed by wind are very small and light in weight.
Cotton and Calotropis seeds have hairs over the seeds which help them to be carried away by the wind.

So the correct answer is option C.

Note: Seed dispersal is important for plants because it prevents competition between the plant and its own seedlings for sunlight, water, air and minerals and provides new habitats for wider distribution.