Hordeum is a genus of annual and perennial plants in the grass family. They are native throughout the temperate regions of Africa, Eurasia, and the Americas. One species, H. vulgare (barley), has become of major commercial importance as a cereal grain, used as fodder crop and for malting in the production of beer and whiskey. Some species have become weeds introduced worldwide by human activities, others have become endangered due to habitat loss. Hordeum species are used as food plants by the larvae of some Lepidoptera species, including the flame, rustic shoulder-knot and setaceous Hebrew character. The name Hordeum comes from the Latin word for "to bristle" (horreō, horrēre), and is akin to the word "horror".

Species

Species include:

Formerly included species

Botanists now regard many species as better suited to other genera: Arrhenatherum, Crithopsis, Dasypyrum, Elymus, Eremopyrum, Hordelymus, Leymus, Psathyrostachys, and Taeniatherum.