The aleurone layer surrounds the endosperm tissue of grass seeds. In the cultivated cereals it is usually single-layered (except in barley). In cereals with starchy endosperm, the aleurone contains about 30% of the kernel's proteins. In multicolored corn, anthocyanin pigments in the aleurone layer give the kernels a dark, bluish-black color.
During seed germination, the plant embryo produces the hormone gibberellin that triggers the aleurone cells to release enzymes for the hydrolysis of starch and storage proteins into the endosperm. The breakdown of the starchy endosperm supplies sugars to drive the growth of roots and the acrospire. This effect is inhibited by the plant hormone abscisic acid, which keeps the seed dormant.