Most spikelets contain two seeds, each enclosed by a husk called the hull. The hull must be removed before the seeds can be processed into oatmeal or other food products. The oat seed, called a groat, is usually the same color as the hull. Different varieties of oat seeds may be white, yellow, red, gray, or black. The chief kinds of cultivated oats include common oats, red oats, side oats, and hull-less oats.
Common oats are the type most widely grown in the United States.
Red oats have reddish seeds. Side oats have all their branches on one side of the stalk. Hull-less oats, unlike the other types, have loose husks that separate from the seeds during harvesting. Oats can be grown in a variety of climates and soils. But they grow especially well in areas that have a cool, moist climate and fertile soil.