Although there are as many as seventy-two Trigonella species, most studies on seed structure and physiology have been performed on the Trigonella foenum-graecum L. (fenugreek).
Fenugreek seeds are surrounded by the seed coat. The seed coat is separated from the embryo by a well developed endosperm, which is the principal storage organ. In mature seeds the majority of the endosperm cells are nonliving, the cytoplasmic contents of which are occluded by the store reserves: galactomannan. This tissue is surrounded by a one cell layer of living tissue: the aleurone layer. The aleurone layer cells are small and thick walled and contain aleurone grains, which disappear during the course of seed germination (Reid and Meier, 1972; Bewley and Black, 1994).