Question

Define germination? Name the two types of germination. Explain with examples.

Answer 1

The growth and development of the embryo present in the seed into a seedling (or a young plant capable of independent existence) is called as seed germination. The embryo in a seed remains inactive or dormant. When the seed is put into the soil and given water and under suitable temperature, the embryo becomes active on absorbing the water and the embryo turns into a seedling.
Types of germination — There are three types of germinations.
(i) Epigeal
(ii)Hypogeal
(iii) Viviparous

(i) Epigeal germination — Epi means above; geo-ground (earth) When the cotyledons in growing seed come out of the soil it is an epigeal type of germination as in case of castor seed, cucumber, tamarind, bean seed the cotyledons come out of the soil and turn green. These are called cotyledonary leaves. This canyon photosynthesis till new leaves arise. .

(ii) Hypogeal germination—Hypo-below, gea soil. When in a growing seed the cotyledons remain under the ground as in the case of a gram, pea, groundnut, and maize. The plumule firms the aerial shoot to which bears leaves and the radicle gives rise to roots. The growing seedling gets food from the cotyledons. As the seedling grows the cotyledons die in the soil.

(iii) Viviparous germination—This is a special type of germination. This occurs in plants growing along the sea coasts and in salt lakes. The seed starts growing while it is still attached to the plant as in mangrove plants. The embryo comes out of the fruit with a long, dart-like radicle. It falls directly into the soft, slushy, wet mud. The radicle gives root and establishes as a seedling and the plumule gives rise to shoot. This is in mangrove plants.