Dispersal of fruit and seeds
Dispersal of fruit and seeds
As we know, plants are fixed to the ground, therefore they must develop mechanisms for the dispersal of their fruit and seeds.The dispersal of fruits and seeds take place by different methods.This methods help in the dispersal of seeds.The methods of dispersal given as following:-
- Dispersal of seeds and fruits with the help of external agencies like water, wind and animals.
- Dispersal by plants itself using its internal mechanism.
Dispersal with the help of external agencies
Wind, water and animals are the external agencies which involved in the dispersal of seeds and fruits at different places.
(a) Dispersal by wind(Anemochory):- Seeds and fruits are thrown away by the help of wind to suitable places for germination.The plants acquired certain adaptations for dispersal of seeds by wind.
Many plants produce very light and small seeds and fruits which carried away easily by wind for example grasses and orchids.While some plants produce flattened and winged seeds which carried away by wind, Dalbergia etc.
Many plants produce hairy seeds which help in their dispersal.When these seeds reach where sufficient moisture is present in the air, the hairs collapse and the seeds settle down.Some other mechanism also adapted by plants.
Dispersal by water(hydrochory)
Another external agency of dispersal of seeds and fruits is by the help of water.The aquatic plants that grow along beach side and along the bank of river the seeds and fruits are dispersed by the water.The plants present on slopes the seeds and fruits are carried to distant place by water
The fruits and seeds which dispersed by water develop some certain mechanism which provide them buoyancy and help in floating.
Such as the Coconut fruits are fibrous and enclose air which helps them in floating.The fruits of Lotus are dispersed by the same mechanism.Similarly, in case of Nymphaea the seeds are buoyant due to presence of air spaces in the testa.
Dispersal through animals(Zoochory):-Animals including the man also facilitates the dispersal of seeds and fruits. The plants acquired some special adaptations which help in the dispersal of seeds and fruits by the animals.
i. Development of sticky fruits:-Some plants produce sticky fruits because their fruits wall excrete some glands.These fruits get stick to the bodies of animals and clothes of the human beings and are carried away different places e.g Boerhaavia diffusa.
ii. Development of sticky seeds:- In some plants, e.g Cordia the fruits produce sticky seeds.When birds feed on fruits the seeds stick to their beaks and feathers and cannot be shaken off easily.These birds fly to other places and they rub their beaks against hard surface.Some seeds develop spines which cling to the fur of animals or clothes of the humans and get dispersed.
Dispersal by plant itself
Many fruits when ripe suddenly burst and the seeds are thrown to some distance from parent plant such fruits act as explosives.
In succulent fruits the ejection of seeds depends upon the extreme turgidity in the parts of fruits on maturity.In Squirtinh cucumber the pulp of the fruit changed into a thick liquid mass and the fruit wall become stretched.At slight disturbance the fruit gets free from the stalk and seeds along with mucilaginous fluid are forced out through the pore with great force