the name of the fruits of several grasses, as corn, wheat, barley, oats and rye. They contain gluten, starch, a sweet mucilage, an aromatic substance in the hulls, and much moisture. Grains furnish one of the chief foods of man, being ground into meal and flour, which are included in most articles of diet. The term grain is also used to designate the plants themselves. The raising of grains is among the chief agricultural industries. The most productive regions are the valleys of great rivers, such as the Nile, the Po and the Ganges, in the Old World, and the Mississippi, in the New World. The prairie region of the United States is the greatest grain-producing region of the world. The most important grains are shown in the accompanying color plate and are described under their respective titles.