Dispersal of Fruits and Seeds:
Usually a plant produces a large number of fruits and seeds. Some fruits are carried from one place to another by human beings for their own interest e.g. Litchi, Mango, Jackfruit etc. In some plants fruits and seeds remains just under the tree. Again in some plants fruits and seeds are taken away from the mother plant by various agents and are distributed to distant areas. This process of distribution of fruits and seeds to a distant area from its mother plant by several means is called dispersal of fruits and seeds. Usually dispersal of fruits and seeds take place by the following means. Here is a brief discussion.
1. Dispersal by wind: Seeds of many plants are carried away by wind and aredistributed at distant places. These types of fruits and seeds are very light, small and provided with wings. So the wind may carry these seeds easily to different places. Fruits of sunflower have pappus, in Chhagalbati the style is persistent and feathery, in Mehogany and Shajina there is flat appendage in the seeds. The seeds of Akonda and Chhatim are provided with hairs. Thus fruits and seeds of these plants can easily travel by wind and can be scattered to distant places. Occasionally we find seeds of Chhatim and Akonda are flying in the wind.
2. Dispersal by water: Shapla, Padma or even coconut float on water andmoves to distant places. Fibrous or spongy tissues cover their fruits and seeds, thus they float on water very easily.
3. Dispersal by explosion of fruits: There are some fruits, which produce avibration when it burst. By vibrating force the seeds are scattered to a good distance. Castor, pea, Dopati etc. are fruits of these types.
4. Dispersal by Animals: Fruits of some plants adhere to the body of animalsand are carried away from one place to another. Fruits of Prem Kata(chrysopogon Aciculatus), Have Sticky Glands On Their Bodies, Khagra (Xantiuun indicum) has hooks on its body, etc. are dispersed by adhering toanimal body even to clothing of human beings.
5. Dispersal by Birds: Some fruits are carried away by birds on their beaks to agreat distance. Litchi is one of these types of fruits. Birds eat some fruits but its seeds cannot be digested and come out with stools and from that seedlings grow, e.g. Date-palm, Pisum, Tamarind, Ficas etc.
Besides these, man willingly carried many fruits and seeds from one place to another, even from one country to another.
Without favourable conditions seed do not germinate. Again without favourable environment no seedling can grow big. If all the fruits or seeds of a plant fall directly under the mother tree, then many of them will fail to germinate, for want of space, water, light and air, many of the germinated ones may die because of the shade of the plants. The rest survivors will gradually perish. So for maintaining the existence and increasing of generation of plants in favourable environment dispersal of fruits and seeds is essential.