Structure and development of cereal grains

The grains of cereals are single-seeded fruit. They have similar patterns of development with the mature grain being composed of the triploid endosperm tissue and diploid embryo surrounded by tissues of maternal origin, notably the testa (seed coat) and pericarp (fruit coat). The embryo comprises the embryonic axis (which develops to form the seedling) and a single cotyledon called the scutellum. The endosperm is the major storage tissue and comprises central starchy endosperm cells surrounded by one or more layers of aleurone cells. The starchy endosperm cells die during the later stages of development but the aleurone cells remain alive and, with the scutellum, contribute to the mobilization of storage reserves during germination. Despite these similarities, there is wide diversity in the structure of the mature grains, including size, morphology, and proportions of tissues. These differences underpin the behavior of the grains during processing.