178. Eriogonum rotundifolium Bentham in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 21. 1856.
Round-leaf wild buckwheat
Eriogonum cernuum Nuttall subsp. glaucescens S. Stokes; E. cernuum subsp. rotundifolium (Bentham) S. Stokes; E. rotundifolium var. angustius Goodman
Herbs, spreading, annual, 0.5-4 dm, glabrous and often glaucous, greenish to grayish. Stems: caudex absent; aerial flowering stems erect, solid, not fistulose, 0.1-0.5(-0.7) dm, glabrous. Leaves basal; petiole 1.5-4 cm, floccose; blade cordate to orbiculate, 1-2(-3) × 1-2.5(-3) cm, densely white-tomentose abaxially, floccose or subglabrous and greenish adaxially, margins plane. Inflorescences cymose, open to diffuse, usually flat-topped, 5-35 × 5-35 cm; branches glabrous; bracts 3, scalelike, 1-2.5 × 0.5-2 mm. Peduncles erect, straight, stoutish, 0.3-1.5 cm, glabrous. Involucres turbinate to campanulate, 1-2 × 1.5-2.5 mm, glabrous; teeth 5, erect, 0.4-0.8 mm. Flowers 1-2.5 mm; perianth white to pink with greenish to reddish midribs, becoming rose to red, glabrous; tepals dimorphic, those of outer whorl flabellate, those of inner whorl lanceolate; stamens included, 1.2-1.7 mm; filaments pilose proximally. Achenes dark brown, 3-gonous, 1.5-2 mm, glabrous. 2n = 40.
Flowering May-Oct. Sandy to gravelly flats and slopes, mixed grassland, saltbush, creosote bush, and mesquite communities, juniper woodlands; 600-1800 m; Ariz., N.Mex., Tex.; Mexico (Chihuahua, Coahuila).
Eriogonum rotundifolium is the southern counterpart to E. cernuum, being common to abundant and occasionally even weedy. Its overall range, however, is significantly smaller. It occurs in Arizona only in Cochise County, but is found more widely in New Mexico, and is common in the trans-Pecos region of western Texas, with scattered populations in Dimmit, Ector, Foard, and Knox counties outside that region.
A sterile Edwin James specimen gathered in 1820 (NY) supposedly was collected near the Rocky Mountains and may be Eriogonum rotundifolium. Also seen at NY is an unattributed, redistributed collection of this species labeled only “Colorado.” Until better documented material from that state is seen, the species is considered not to be a member of the Colorado flora.
F. A. Elmore (1943) reported that the round-leaf wild buckwheat was used by the Navajo (Diné) people as an emetic. My own consumption of a few seeds, as a self-experiment, produced no particular urge to vomit. Inasmuch as the treatment was taken after swallowing ants, it is difficult to know whether the ants or the seeds were the emetic. G. M. Hocking (1956) reported that the leaves were used for sore throats and the stems were eaten raw (the latter proving in the same self-experiment not to be particularly tasty, leaving a slightly sour aftertaste). Hocking also reported that the roots were used medicinally but mentioned no specific ailment.