cotyledons , or seed leaves, of the embryo. Cotyledons are not true leaves, but in many plants, once above ground, they carry on photosynthesis until the first leaves of the newly sprouted plant develop. The cotyledons absorb nutrients from the endosperm that nourish the embryo. The cotyledons of many species are also specialized to store some of these nutrients as protein, lipids, or starches that are broken down later to support the growth of the embryo into a seedling.During seed formation, genes that encode storage proteins and the enzymes of starch and fat formation are highly active in the endosperm or cotyledons. The nutrient reserves will nourish the embryo when it begins to grow into a new plant.Next the embryo elongates quickly. Cells in the embryo divide rapidly. The new cells begin to differentiate into specialized structures. Cells between the cotyledons become the embryonic shoot, which will later produce the stem and leaves
