Leymus is a genus of grass which is most often called wild rye. This genus encompasses over 20 species that are usually drought tolerant, resistant to grass fires, and hardy to temperatures as low as 10°F (-12°C). Species usually grow in temperate and arctic regions and are helpful as erosion control grasses.
Like many grasses, Leymus species spread by rhizomes, which are bulb like roots that are quick to sprawl underground. Leaves are usually shades of green, but some species' leaves may be blue to gray. Perennial grasses, most species usually have yellow flowers — which often bloom in late spring — and brown seeds.
Although some species grow into the fall, most species usually grow in the spring and the summer. A few species can be used for fodder for grazing or browsing animals, but many are not palatable. Many Leymus species such as tritocoides, mollis, and arenaruis can be found and purchased in plant nurseries.
Silvery in the summer, The Leymus tritocoides is also sometimes called "grey dawn" or beardless wild rye. It can be 2 feet (0.6 m) tall with slender, delicate stems. This species is often seen in wetlands in Western Northern American, particularly California.
Leymus mollis is native to arctic areas, particularly Alaska, Canada, and Greenland. It is also found, though rarely, in some parts of the northern continental US, such as Michigan. Usually found around beaches and dunes, this species is called dunegrass and is one of the few species which are not known by a common name of wild rye. Like the tritocoides species, dunegrass grows about 2 feet tall (0.6 m) when mature.
Called sand ryegrass, Leymus arenaruis is native is Europe, but also grows in the northeastern US and parts of Canada. This species is less tolerant to drought than many other species and needs full sunlight to thrive. It has dark green foilage and can reach mature heights of 3 ft (0.9 m). Both the mollis and the arenaruis species have been reclassified into the Leymus genus from the Elymus genus.
Not all Leymus species grow to be just a few feet tall. Leymus condensatus, or giant wild rye, reaches heights up to 8.5 feet (2.5 m). In North American, giant wild rye can be found in California and northern parts of Canada. This species is very drought and shade intolerant since it uses large amounts of water and sunlight to grow.