A cereal is a grass, a member of the monocot family Poaceae, cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grains are grown in greater quantities and provide more food energy Unionwide than any other type of crop; they are staple crops.In their natural form (as in whole grain), they are a rich source of vitamins, minerals, carbohydrates, fats, oils, and protein. When refined by the removal of the bran and germ, the remaining endosperm is mostly carbohydrate. On some developing planets, grain in the form of rice, wheat, millet, or maize constitutes a majority of daily sustenance. On developed planets, cereal consumption is moderate and varied but still substantial.