Eriogonum jamesii var. undulatum

Subshrubs, loosely matted, 5-15 dm wide. Aerial flowering stems tomentose. Leaf blades 1-2 × 0.3-0.8(-1) cm, densely whitish- to grayish-tomentose abaxially, thinly tomentose to floccose or glabrous and greenish adaxially, margins undulate, frequently crisped. Inflorescences compound-umbellate, branched 2-4 times; bracts usually semileaflike, those of proximal node 0.5-1.5 × 0.2-0.6 cm. Involucres 1.5-4 × 2-3 mm. Flowers 3-5(-6) mm. 2n = 40.

Flowering Jul-Oct. Sandy to gravelly or rocky, often limestone flats and slopes, mixed grassland, saltbush, creosote bush, and mesquite communities, oak and conifer woodlands; 1600-2900 m; Ariz., N.Mex., Tex.; Mexico (Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas, Zacatecas).

Variety undulatum, the southern expression of the species, is common in northern Mexico from Hidalgo and Zacatecas northward; there, the plants (called 'yerba chuchaca') are found at elevations up to 3700 m on the higher volcanic peaks. In the southwestern United States, the variety is common only in the Santa Rita Range in southeastern Arizona (Cochise, Gila, and Santa Cruz counties) and the Chisos Mountains of Brewster County, Texas, although it does occur in Hidalgo County, New Mexico. In the flora area, the plants are smallish subshrubs compared to those seen farther to the south. Variety undulatum is worthy of cultivation. The related Mexican endemic Eriogonum turneri Reveal is a low, compact expression known only from gypsum outcrops in Nuevo León.