Explanation

In angiosperms (flowering plants), the endosperm is a triploid (3n) tissue that provides nourishment to the developing embryo.

It is formed during double fertilization, where one sperm nucleus fuses with the egg cell to form the zygote, and another sperm nucleus fuses with two polar nuclei in the embryo sac to create the triploid endosperm.

This triploid nature is a key characteristic of angiosperms and distinguishes them from gymnosperms, where the endosperm is haploid.