What is the endosperm of a grain?

In grains, such as wheat, rice, and corn, the endosperm is the starchy, nutrient-rich tissue that makes up the bulk of the grain. It surrounds the embryo and is essential for providing energy to the developing plant. The endosperm is composed mainly of carbohydrates in the form of starch, but it also contains proteins, fats, vitamins, and minerals. During the milling process, the endosperm is often ground into flour or meal, which is used in various food products. Its role is to supply the necessary nutrients for seedling growth until it can photosynthesize on its own.