Endosperm's the tissue produced in the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This makes endosperm an important source of nutrition in human diet. For example, wheat endosperm's ground into flour for bread (the rest of the grain's included as well in whole wheat flour), while barley endosperm's the main source for beer production. Other examples of endosper… (More on Endosperm)