Diarrhena americana, also known as American beak grass or American beakgrain, is a native, perennial grass of North America, where it grows in rich, moist woodlands from Missouri to Maryland and south to Oklahoma and Alabama. It is considered to be threatened in Michigan, and is listed as endangered in Maryland and Wisconsin. Culms range from 60–131 cm in height. Historically, Diarrhena americana was the only species of beak grass recognized in the United States; however studies have suggested that the known beak grass is to be classified into two distinct species, Diarrhena americana and Diarrhena obovata.