endosperm The inner part of cereal grains; in wheat it comprises about 83% of the grain. Mainly starch, it is the source of semolina. Contains only about 10% of the vitamin B₁, 35% of the vitamin B₂, 40% of the niacin, and 50% of the vitamin B₆ and pantothenic acid of the whole grain. See also flour, extraction rate.

endosperm
1. A triploid structure found in many seeds of angiosperms: it frequently stores food materials which are broken down during germination.

2. See EMBRYO SAC and DOUBLE FERTILIZATION.

endosperm A nutritive tissue, characteristic of flowering plants, that surrounds the developing embryo in a seed. It develops from nuclei in the embryo sac and its cells are triploid. In endospermic seeds it remains and increases in size; in nonendospermic seeds it disappears as the food is absorbed by the embryo, particularly the cotyledons. Many plants with endospermic seeds, such as cereals and oil crops, are cultivated for the rich food reserves in the endosperm.

endosperm Tissue that surrounds the developing embryo of a seed and provides food for growth. It is triploid (each cell has three sets of chromosomes), being derived from the fusion of one of the male gametes from the germinated pollen grain and two of the haploid nuclei in the embryo sac. See also alternation of generations

en·do·sperm / ˈendəˌspərm/ • n. Bot. the part of a seed that acts as a food store for the developing plant embryo, usually containing starch with protein and other nutrients.