161. Eriogonum capillare Small, Bull. Torrey Bot. Club. 25: 51. 1898.
San Carlos wild buckwheat
Herbs, erect, annual, (1-)2-4 dm, glabrous. Stems: caudex absent; aerial flowering stems erect, solid, not fistulose, 0.5-1.5 dm, glabrous. Leaves basal; petiole 1-3 cm, sparsely villous; blade obovate to round, 1-3 × 1-3 cm, sparsely villous to hirsute and greenish to grayish on both surfaces, margins plane. Inflorescences cymose, usually dense, 10-30 × 5-35 cm; branches not fistulose, glabrous; bracts 3, scalelike, 0.5-3 × 0.5-2.5 mm. Peduncles erect, straight, slender, 1-3 cm, glabrous. Involucres campanulate, 1-1.5 × 1-1.5 mm, glabrous; teeth 5, erect, 0.2-0.4 mm. Flowers 1-1.6 mm; perianth white with greenish or reddish midribs, becoming pink to rose, glabrous; tepals dimorphic, those of outer whorl pandurate with swollen, auriculate bases, those of inner whorl oblanceolate; stamens included to exserted, 0.8-1.2 mm; filaments glabrous. Achenes shiny brown to black, 3-gonous, 1.3-1.6 mm, glabrous.
Flowering Sep-Oct. Sandy flats and washes, saltbush, greasewood, and mesquite communities; 500-1500 m; Ariz., N.Mex.
Eriogonum capillare is known from southeastern Arizona (Gila, Graham, Greenlee, and Pima counties) and extreme southwestern New Mexico, where it is rare in northwestern Hidalgo County.