siemenkuoren

Siemenkuoren, in Estonian, refers to the seed coat—the protective outer layer of a seed. In flowering plants it develops from the outer integuments of the ovule and, together with the inner integument, forms the testa and tegmen that surround the embryo and endosperm. The seed coat often consists of several layers, including an epidermis and suberized or sclerenchymatic tissue, and may be reinforced by lignin to create a durable external shell.

The coat includes structural features such as the micropyle, a small pore through which water may enter during germination, and the hilum, the scar marking where the seed was attached to the ovary. Its composition and thickness vary among species, influencing how easily water and gases move into the seed and how the seed tolerates desiccation or physical stress.

Functions of the seed coat include protection against physical damage and pathogens, reduction of water loss, and control of germination timing. Some coats contribute to dormancy by being impermeable to water or gases until a triggering condition is met, such as scarification or stratification. Colors and textures of the seed coat can reflect compounds like tannins and other phenolics that may deter predators or pathogens.

Ecologically, seed coat traits affect dispersal and germination strategies, helping seeds survive until conditions are favorable. In agriculture and horticulture, understanding the seed coat is important for managing germination, as some seeds require external treatments to break dormancy or enhance water uptake.