Botany

Plants Seeds Fruit Dispersal



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Seeds and fruits contain the next generation of plants. Some plants like annuals die relying completely on the success of their seeds for the next generation whilst others produce few seeds over their lifetime but those seeds are borne in large pods or fruits to nutrure and protect the embryo until germination.

For most plants, they do not want their progeny competing with them for light, nutrients and water soit is important that fruit and seed are dispersed.

To this end, plants use many surprising methods.

Some produce their seeds in fruit which are eaten by animals. The seeds have thick seed coats which protect them from the harmful acids and actions within the animal's gut and they are deposited away from the parent plant in dung, which means they get a bit of extra fertiliser as well. Others are contained in fruit which dry and split, sometimes with an audible 'pop' , scattering the seed as far as possible away from the parent plant.

Some fruit are carried away by animals as they horde them. Many animals horde fruit and bury them - sometimes forgetting where which means the plant gets its seeds planted for it.

Some plants produce seeds which have means of travelling under their own steam. Dandelion seeds for example have tiny, feathered parachutes which carry the seed long distances in air currents, depositing them in new ground away from their parent plants. They are produced in huge numbers because it cannot be guaranteed that the seed will fall on fertile ground.

Other plants like coconuts produce seeds which are capable of surviving long journeys in water - even salt water. These seeds are protected by an outer husk which floats easily and a thick inner coat with a lot of starch and fats inside. This is how coconuts and other trees manage to get themselve from island to island. 

Other seeds have ingenious methods of ensuring they get dispersed. Some are incredibly sticky and , though they are contained in berries or fruit, they are not intended to be ingested but stick to the beaks of birds. Mistletoe, for example, is eaten by thrushes and blackbirds and the seeds pop out of the fruit as the bird eats it and stick to the beak. The bird has to rub the seeds off on bark - neatly sowing them in crevices as it does so (mistletoe is a semi-parasitic plant and lives on bark of other trees).

Other seeds have barbs, feathers and spikes and are designed to stick to the coats of animals as they pass by and are dispersed in this way. Many dogs and cats arrive home with seeds attached to their coats and this, on the plant's part, is fully intentional.

Plants never cease to amaze in their adaptartions for all parts of the world and all habitats and seed dispersal is particular to groups, species and genera. Aquatic plants produce seeds which can survive long journeys in water, and some are dispersed by any number of  helpers including fish, ducks and aquatic mammals. 

This is why many plants are very successful. They propagate by vegetative means and seed and are the basis of life upon which all other life depends.


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