What comprises the majority of the endosperm?

The majority of the endosperm is composed of starch, a complex carbohydrate that serves as the primary energy reserve for the seedling. Starch grains are stored in the form of granules within the endosperm cells. In addition to starch, the endosperm contains varying amounts of proteins, lipids, vitamins, and minerals, depending on the plant species. The exact composition can influence the nutritional value and functional properties of the grain.