Hilaria is a genus of perennial grasses in the family Poaceae (order Poales), native to arid and semi-arid regions of North America. Members of the genus are commonly known as curly mesquite, a name that reflects their characteristic curled leaf blades and their prevalence in the same desert scrub and grassland habitats as the mesquite tree. The genus was first described by the botanist Carl Sigismund Kunth in 1816, based on specimens collected during Humboldt and Bonpland's expeditions to the Americas.
The genus comprises roughly ten species distributed across the Southwestern United States, Mexico, and Guatemala. Well-known members include Hilaria jamesii (James' galleta), a widespread species of the Colorado Plateau and Great Basin; Hilaria rigida (big galleta), a coarse perennial of Mojave and Sonoran desert washes; Hilaria mutica (tobosa grass), a dominant grass of Chihuahuan Desert grasslands; and Hilaria belangeri (curly mesquite), the species most closely associated with the common name. Several species have also been treated under the genus Pleuraphis, and the placement of individual species between the two genera has varied among taxonomic authorities.
The generic name honors the French naturalist Augustin Saint-Hilaire (1779–1853), a pioneer of Brazilian botany.
Etymology
The genus name Hilaria was given by the botanist Kunth to honor the French naturalist Augustin François César Prouvençal de Saint-Hilaire (1779–1853), who made foundational contributions to the exploration and documentation of South American flora.
Distribution
Hilaria species are native to arid and semi-arid regions of the Southwestern United States (including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas, and Utah), Mexico (ranging from Baja California and Sonora south through Chihuahua, Coahuila, Durango, Zacatecas, and into Oaxaca), and Guatemala. One species, H. cenchroides, has naturalized in parts of southern Arizona.
Ecology
Species of Hilaria are characteristic grasses of desert grasslands, desert scrub, and semi-arid rangelands across the Chihuahuan, Sonoran, and Mojave deserts. They are important forage grasses in these ecosystems and contribute to soil stability in regions prone to wind erosion.
