Question

Write the mode of seed dispersal in calotropis

Answer 1

Answer:

Explanation:1. Very small, dry and dusty seeds as those of orchids (weighing as little as 0.004 mg in some cases—Fig. 460) are carried by wind like pollens. Seeds of Cinchona are also ex­tremely small and at the same time winged.

2. Parachute mechanism:

Certain seeds and a few fruits are provided with appendages which act like parachutes in helping them to float in air.

i) Pappus (Figs. 318 & 461) formed by the modification of the persistent calyx in Compositae and the allied families Dipsaceae and Valerianaceac.

This pappus is of different appearance in different species and in many cases it is large and light enough to keep the cypsela fruit floating in air for a long time.

(ii) Coma (Fig. 462) is a tuft of hair developed as a crown on the seeds of Calotropis, Holarrhena, Alstonia (two tufts) and most plants of Apocynaceae and Asclepiadaceae.

Minute seed of orchid, Parachute-like pappus of dandelion, Coma of Calotropis

(iii) Hairy outgrowths on the testa (Fig. 463) completely cover cotton seeds. Such hair develops from the inner walls of the silk-cotton pod.

(iv) Persistent hairy styles (Fig. 464) of the achenes of Clematis, Naravelia (Fig. 455A), Anemone, etc., help them to float in air.

(v) Balloon type inflated persistent calyx of Physalis enables the entire fruit to float on air for some time. The same purpose is served by the inflated ovaries of the pod of Colutea arborescens (Leguminoseae) and the capsules of the balloon vine (Cardiospermum halicacabum) and also a few other plants of Sapindaceae