Inflorescences: peduncle 3-15(-30) mm, sparingly glandular-puberulent, sparsely to densely spreading-villous; flower cluster 5-10(-12) mm diam. in anthesis; abaxial perianth limb 3-8(-10) mm. Fruits 3-5 mm. Flowering year-round, primarily early spring-late fall. Open arid areas, usually on sandy or gravelly soils, sometimes on gypsum; 0-1600[-2500] m; Ariz., Colo., N.Mex., Okla., Tex., Utah; Mexico; West Indies; Central America; South America. The variety is extremely variable with regard to robustness, density of pubescence, and size of flowers. B. L. Turner (1994) noted that North American collections are indistinguishable taxonomically from South American collections.