62.3. Astragalus nuttallianus DC. var. imperfectus (Rydb.) Barneby, Leafl. West. Bot. 3: 1009. 1942

Type:— USA, Nevada, Nye County, Rhyolite, 17 May 1909, Heller 9637 (holotype (based on Hamosa imperfecta) NY00011921!; isotype: RENO009575 digital image!, PH00013580 digital image!) .

Hamosa imperfecta Rydb., Bull. Torrey Bot. Club 54: 329. 1927.

Leaflets elliptic, none retuse; calyx teeth short, 1–2 mm long; the tube 1.9–2.8 mm long, the trichomes appressed o slightly ascendant, up to 0.8 mm long.

Distribution:— Northwestern Mexico, Baja California in northeastern (Cucupa Mts.), at El Mármol, 12 km N to Santa Ynés Ranch (29°53’N – 114°51’W); in Sonora, isolated at the northwestern, adjacent to the Pinacate Volcano (31°46’N – 113°26’W) and isolated also in San Carlos Bay (27°58’N – 111° 04’W). Also, in Colorado, Utah, California, and Arizona (USA) (Fig. 19).

Habitat:— Adjacent to coastal dunes; gravel soils; bottom of canyons; stony plains; alluvial plains; desert scrubland; 1–420 m.

Specimens examined:— BAJA CALIFORNIA: 18 April 1905, Crater, Arrobrito, Cucapa Mts., D. MacDougal 203 (NY), 24 February1973, Agua Dulce, R. Moran 20260, J. L. Reveal (NY); SONORA: 15 April 1992, Campo Rojo, east side of Pinacate volcanic field, R. S. Felger 92-481B, S. W. Whitely (MEXU, NY) ; 15 May 2010, Ánimas Valley, 58.7 km (byr air) E. of Agua Prieta, Cuenca Los Ojos Foundation property, T. R. Van Devender 2010-406, A. L. Reina, C. Roll (MEXU, USON) ; 23 March 1970, Mpio. Puerto Peñasco, ca. 0.5 km S of Pinacate Peak, Sierra Pinacate, R. S. Felger 19310 (USON 15 April 1992, Campo Rojo, east side of Pinacate volcanic field, R. S. Felger 92-481B. S. W. Whitely (MEXU).