endosperm

The storage tissue in the seeds of most angiosperms, derived from the fusion of one male gamete with two female polar nuclei. The endosperm is a compact triploid tissue, lacking intercellular spaces and storing starch, hemicelluloses, proteins, oils, and fats. Seeds containing an endosperm or *perisperm at maturity are termed albuminous, whereas those lacking such tissue are termed *exalbuminous. See also aleurone layer.