The New Student's Reference Work/Endosperm

En'dosperm (in plants). A food-tissue within the embryo-sac (which see) of seed-plants and used by the embryo. It makes up the bulk of many seeds, as in pines and the cereals, and contains stored food of various kinds, prominent among which is starch. It is sometimes soft and mealy, and in other cases it is horny. In the so-called vegetable ivory it is as hard as the name suggests. An obsolete name for it is albumen. In the alternation of generations (which see) it is a gametophyte, and being associated with the egg it evidently is a female gametophyte. See Seed.