Sunday, 27 May 2012


A seed contains the young plant embryo within a protective seed coat.  Within it is all the necessary material to produce a new plant, given the right environmental conditions.  Most plants reproduce through the dispersal of their seeds. 

There is an enormous diversity in the sizes of seeds of plants.  Seeds come in all shapes and sizes, from the tiny seeds of orchids to the golf ball sized seeds of the avocado. Even within a single genus of plants, seeds may vary greatly in size.  

Variations in seed sizes occur as plants adapt to different dispersal methods.  Seeds that are dispersed by wind such as dandelions and sycamore are small and light. Burdocks and cleavers have tiny hooks on their seed coats which catch on passing animals and hitch a lift.  Some seeds, including many fruits, are enclosed in a tasty flesh which is attractive to animals and subsequently dispersed by them through there droppings or burial. Plants such as peas or laburnum burst open and disperse their seeds in all directions.  Poppies are shaken by the plant to disperse tiny seeds.  Other seeds such as coconuts are waterproof and can float.  

Some plants produce many small seeds to increase the chances of new plants germinating and surviving. Others produce a large, single seed.  Larger seeds have a competitive advantage over smaller seeds as they have material available to them that makes up for the lack of resources in the environment.  They are capable of faster growth and can grow in poor soils.  They can survive burial by litter and their thicker seed coat enables them to avoid desiccation during dry spells and insulate during cold spells.

The largest seed in the world can take ten years to develop and can grow up to 45 cm long and weigh up to 40 pounds. This is the seed of the Seychelles coconut.  The fruit of this palm looks like two coconuts joined together and so is also known as 'double coconut'.

These coconuts grow on palm trees found only in the Seychelles Islands near Africa.  Growing near the seas, these coconut seeds often fall into the ocean and float away to be washed up on distant shores.

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