- Books Name
- CBSE Class 7 Science Book
- Param Publication
- CBSE Class 7
4. Seed Dispersal
(i) Seeds are dispersed to different places by means of some special structure through wind, water, animals etc.
(ii) Dispersal of seeds is very essential, if all seeds fall at the same place and grow than it will cause competition between germinating seeds for space, nutrients, water, sunlight, minerals etc. and seed would not grow into healthy plants.
(iii) Thus, seed dispersal prevents overcrowding and competition between the plant and its own seedlings for sunlight, water and minerals.
(iv) It also enables the plants to invade new habitats for wider distribution.
(v) Winged seeds such as those of drumstick and maple. (a) and (b)], light seeds of grasses or hairy seeds of aak (Madar) and hairy fruit of sunflower. (a), (b)], get blown off with the wind to far away places.
(vi) Some seeds are dispersed by water. These fruits or seeds usually develop floating ability in the form of spongy or fibrous outer coat as in coconut.
(vii) Some seeds are dispersed by animals, especially spiny seeds with hooks which get attached to the bodies of animals and are carried to distant places. Examples are Xanthium and Urena.
(viii) Some seeds are dispersed when the fruits burst with sudden jerks. The seeds are scattered far from the parent plant. This happens in the case of castor and balsam.