During the early stages of embryo development, the endosperm is free nuclear, and becomes cellular during the late spherical stage. As the embryo matures, the central portion of the endosperm is digested and only a single layer of endosperm cells remains in the mature seed. The ovule continues to enlarge to accommodate the growing embryo. Much of the nucellus in the micropylar and chalazal regions is digested by the growing endosperm. The remaining lateral cells of the nucellus continue to enlarge as the seed matures and perisperm starch IS accumulated in two flat lateral wings of the seed. The mature seed is dorso-ventrally flattened, with the embryo outline visible on the dorsal surface