Dispersal is the phenomenon of transferring Plant parts from one place to another. Dispersal of fruits and seeds are a very common feature in angiosperms which have great importance in their life process because of the following facts.
For these above facts, there will be the theory of the struggle for existence, thereby most of the seedlings will become very weak and liable to perish under such unfavourable conditions. Still, the natural hazards (floods, drought etc) may destroy the total plant population. Most of the plants depend on some external agents for their seed dispersal. In some plants, the fruits are provided with some explosive mechanism for achieving their goal.
Plants that require wind for their dispersal agent are called anemochorous types. For this wind dispersal, the seeds should be very light in weight, so that their lower buoyancy rate may help them to fly in the air for long distances. Following adaptation, the system helps to disperse seeds for long distances away from the mother plant.
Seeds of some plants are very minute, dry and light in weight and are easily dispersed by the wind from one place to another, e.g. Orchids (one seed of orchid weight about 0.004mg), grains (fruits and seeds) of grasses etc (Fig 1.1 A).
Different types of Wing-like structures develop on various types of fruits and seeds of some plants – these help them to float in the air.
some Appendage type structures develop on some fruits and seeds, which act as parachutes. By helping with this they remain in the air for a long time and can disperse for a long distance. The appendages are:
In this type of mechanism very small seeds are liberated slowly from the fruit through minute pores. e.g. Antirrhinum manus of Scrophulariaceae etc.
The plants growing on the bank of a river or sea-shore, disperse their seeds and fruits with the help of water current for a long distance. Floating devices in the form of fibrous or spongy water-proof coats present in these types of fruits and seeds. The plants which have required water as an agency for dispersal are called hypochlorous.
The fruitlets may lie embedded in the spongy thalamus because in this way they can be carried away to another by the help of water current,e.g. lotus, Nelumbo nucifera if Nymphaeaceae etc.
The fruits and seeds with their adhering structures are dispersed by animals, such devices are called zoochorous.
Dry fruits and seeds –
Many dry fruits and seeds have spines, barbs, bars or sticky glands but means of which they can attach themselves to the body of animals or human beings and thus be transported to a distant place. Fruits may provide with:
Fleshy fruits –
Fleshy fruits possess beautiful colour or test or both, inviting the animals especially the birds. These animals and birds disperse fruits and seeds in the following ways.
In some cases, the pericarp of fruit – after ripening and drying – becomes stretched due to some external pressure in contact with air, water drops etc.
That’s it for this post. If you have any query please feel free to comment below. Thank you.
Dispersal is the phenomenon of transferring Plant parts from one place to another.
Plants that require wind for their dispersal agent are called anemochorous types.
ধারণা (Concept) সাহিত্যের ক্ষেত্রে 1990 খ্রিস্টাব্দের শেষের দিকে অথবা 2000 খ্রীস্টাব্দের শুরুতে শিখণ নকশাটির ধারণার উল্লেখ পাওয়া যায়। শ্রেণীকক্ষে পাঠ…
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