The endosperm is usually triploid and develops from the primary endosperm nucleus, the triploid nucleus resulting from the fusion of one of the male gametes from the pollen tube with the polar nuclei in the embryo sac.

• 胚乳通常是三倍体，由初生胚乳核发育而来，三倍体核来源于花粉管中的雄配子与胚囊中两个极核的融合。