Rye (Secale cereale) is a grass grown extensively as a grain, a cover crop and as a forage crop. It is a member of the wheat tribe (Triticeae) and is closely related to barley (Hordeum) and wheat (Triticum). Rye grain is used for flour, rye bread, rye beer, crisp bread, some whiskeys, some vodkas, and animal fodder.ye bread, including pumpernickel, is a widely eaten food in Northern and Eastern Europe. Rye is also used to make crisp bread. Rye flour is high in gliadin but low in glutenin. It therefore has a lower gluten content than wheat flour. It also contains a higher proportion of soluble fiber.