Eremalche is a small genus of three species of annual herbs in the mallow family (Malvaceae), endemic to the desert southwest of North America. Plants are erect or ascending annuals, more or less pubescent, with stems that are often purplish and apparently hollow. The leaves are orbicular in outline and crenate-dentate to more or less deeply lobed. Flowers are borne singly or in small clusters in the leaf axils, sometimes aggregated toward the stem tips; each flower has a trimerous involucel of linear bractlets, a 5-lobed calyx, and five petals that range from white to pink or rose-purple. The staminal column is glabrous and styles number 12–35. The fruit is a disk-shaped schizocarp, glabrous, breaking into 12–35 semi-circular, indehiscent, ridged, blackish mericarps, each containing a single seed. The genus ranges across the southwestern United States into northwestern Mexico, growing in arid desert habitats. Notable members include Eremalche rotundifolia (desert five-spot), named for the distinctive purple spot at the base of each petal, Eremalche parryi (Parry's mallow), and Eremalche exilis (white mallow). A California endemic sometimes called Eremalche kernensis is today generally treated as a subspecies of Parry's mallow.
Etymology
The name Eremalche derives from the Greek eremiche, meaning "of the desert," a direct reference to the arid desert habitats in which all species of this genus occur.
Distribution
Eremalche is endemic to the desert southwest of North America, with species distributed across the southwestern United States and into northwestern Mexico. The genus is absent from more mesic regions and restricted to arid, open desert environments.
Taxonomy Notes
The genus comprises three accepted species: Eremalche rotundifolia, Eremalche parryi, and Eremalche exilis. A fourth taxon, Eremalche kernensis (the Kern mallow, a California endangered plant), is generally treated today as Eremalche parryi subsp. kernensis rather than a distinct species. The genus was monographed by Paul A. Fryxell in his 1994 treatment of Malvaceae for the Journal of the Arizona–Nevada Academy of Science.
