ABSTRACT
A seed is the fertilized and matured ovule of angiosperms and gymnosperms and represents a crucial stage in the life cycle of seed-bearing plants. Seeds of diverse plant species may display differences in size, shape, and color. Despite apparent morphological variations, most mature seeds consist of the following three major components: the embryo, the endosperm, and the testa (seed coat; Figure 9.1). The embryo consists of leaf, stem, and root precursor tissues. Growth of the embryo out of the seed leads to the formation of a seedling. The endosperm is the tissue that surrounds the embryo and provides nourishment for the development and growth of embryo and seedling. In some seeds, the endosperm is reduced to a few cell layers or may completely disappear at maturity. In these seeds, food reserves are stored in cotyledons. The testa surrounds the embryo and endosperm and provides a protective covering for the seed.
