As nouns the difference between endosperm and flower

is that endosperm is (biology) tissue surrounding the embryo of flowering plant seeds, that provides nutrition to the developing embryo; usually triploid while flower is a colorful, conspicuous structure associated with angiosperms, frequently scented and attracting various insects, and which may or may not be used for sexual reproduction or flower can be something that flows, such as a river.

As a verb flower is

to put forth blooms.