Hordeum

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:
 * Hordeum aegiceras – Mongolia, China including Tibet
 * Hordeum arizonicum US (CA AZ NV NM), Mexico (Baja California, Sonora, Durango)
 * Hordeum bogdanii – from Turkey and European Russia to Mongolia
 * Hordeum brachyantherum – Russia (Kuril, Kamchatka), Alaska, Canada including Yukon, US (mostly in the West but also scattered locales in the East), Baja California
 * Hordeum brachyatherum – Chile
 * Hordeum brevisubulatum – European Russia; temperate and subarctic Asia from Turkey and the Urals to China and Magadan
 * Hordeum bulbosum – Mediterranean, Central Asia
 * Hordeum californicum – US (CA; OR; NV)
 * Hordeum capense – South Africa, Lesotho
 * Hordeum chilense – Argentina, Chile (including Juan Fernández Is)
 * Hordeum comosum – Argentina, Chile
 * Hordeum cordobense – northern Argentina
 * Hordeum depressum – US (CA; OR; WA; ID; NV), British Columbia, Baja California
 * Hordeum distichon – Iraq
 * Hordeum erectifolium – northern Argentina
 * Hordeum euclaston – Brazil, Uruguay, Argentina
 * Hordeum flexuosum – Uruguay, Argentina
 * Hordeum fuegianum – Tierra del Fuego
 * Hordeum guatemalense – Guatemala
 * Hordeum halophilum – Argentina, Chile, Bolivia, Peru
 * Hordeum intercedens (bobtail barley) – California, Baja California
 * Hordeum jubatum (foxtail barley) – widespread in US and Canada; Asiatic Russia, Inner Mongolia, Central Asia, Caucasus
 * Hordeum × lagunculciforme – Iraq, Turkmenistan, Himalayas, western China
 * Hordeum lechleri – Argentina, Chile
 * Hordeum marinum (sea barley) – Europe, North Africa, southwestern and central Asia
 * Hordeum murinum (wall barley) – Canary Islands, Europe, North Africa, southwestern and central Asia
 * Hordeum muticum – Argentina, Chile, Bolivia, Peru
 * Hordeum parodii – Argentina
 * Hordeum patagonicum – Argentina, Chile
 * Hordeum × pavisii – France
 * Hordeum procerum – Argentina
 * Hordeum pubiflorum – Argentina, Chile
 * Hordeum pusillum (little barley) – widespread in Canada and US; northern Mexico, Bermuda, Argentina
 * Hordeum roshevitzii – China, Korea, Primorye, Mongolia, Siberia, Kazakhstan
 * Hordeum secalinum – Europe, Mediterranean, Caucasus
 * Hordeum spontaneum – from Greece and Egypt to central China
 * Hordeum stenostachys – Brazil, Argentina, Uruguay, South Africa
 * Hordeum tetraploidum – Argentina, Chile
 * Hordeum vulgare (barley) – native to the Middle East, now cultivated in many countries

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