testa (botany)

A seed coat or testa (Latin for vessel shell ) surrounds and protects the plants located in the interior of the embryo. It is formed after fertilization of the ovule from which the ovule integument surrounding. Also two integuments ( inner and outer ) are possible; this is the case, both or only one may be involved in the formation of the seed coat. Does it show only from the inner integument, they are called tegmen (Latin: coverage); it is made only from the outside, it is called a testa.

The outermost epidermal layer is referred to as Exotesta and the innermost as endotesta. In between, one or more layers may be, referred to collectively as Mesotesta.

If the seed coat very hard, one speaks of a Sklerotesta (gr / lat: . Dry, hard container ). Frequently, the hard shell is made of intergrown seed and fruit bowls. The seed coat can also differentiate into an inner Sklerotesta and a fleshy outer Sarko Testa.

If the seed coat a high proportion of sugars, which swell to a mucus during germination, is spoken by a Myxotesta.

In addition to the protection of the embryo, the seed coat serve through training of certain structures of the propagation of seed:

• For example, the hairs of the cotton seed to be regarded as derivatives of the seed coat. These are originally in the service of the spread of cotton seed by the wind ( called Anemochorie ).
• Another example is the red fleshy structures surrounding the seed of yew ( Taxus baccata). This is not a fruit in the botanical sense, but rather a transformation of the seed coat to a so-called arils, which ( here mainly of birds ) is the attraction of animals on the seeds after digestion of the red, fleshy aril elsewhere eliminated in the feces and so contribute to the spread of the seed ( Zoochorie ).

Swell

• Plant morphology
• Plant propagation