Wheatthe world's most important grain crop Wheat is a grass-type plant that belongs to the group of grains called cereals, which also includes rice, oats, corn, barley, and rye.A common food staple in North and South America, Europe, Africa, Australia, and much of Asia, wheat covers more of the earth's surface than any other food crop.heatthe world's most important grain crop Wheat is a grass-type plant that belongs to the group of grains called cereals, which also includes rice, oats, corn, barley, and rye.