Dormancy in Seeds of Charlock: I. DEVELOPMENTAL ANATOMY OF THE SEED

The anatomy of the embryo, endosperm, and testa throughout the development of charlock seeds is described. In mature seeds the embryos are morphologically fully differentiated. Each embryo consists of a shoot meristem with two large cotyledons but no leaf primordia, and a root meristem with a root cap. The embryo is surrounded by a single layer of aleurone-like cells derived from the endosperm and enclosed within the testa. Mucilages and phenols which could greatly retard the diffusion of oxygen into the tissues of the embryo are found in the testa. Dormancy, which appears to be induced by a shortage of oxygen, is probably associated with the presence of these covering layers.