44.2. Astragalus humistratus A. Gray var. sonorae (A. Gray) M. E. Jones, Contr. W. Bot. 10: 58. 1902

Type:— MEXICO, Sonora, Mountain valleys, between the San Pedro and the Sonoita, September 1851, Wright 1005 (holotype: GH00263299 digital image!; isotype MO149241 digital image!, GH00245337 digital image!) .

Prostrate, annual with single stems (A. L. Reyna 2009-56 et al. (USON)), and with purple and white flowers.

Distribution:— This variety has a larger distribution, along the northern border of Sonora, from Sonoita, through Santa Cruz, Cananea, Nogales to Agua Prieta and isolated in central-western Chihuahua (Guerrero). Also found in Arizona and New Mexico (USA) (Fig. 12).

Habitat:— Intermountain valleys; igneous and alluvial soils; steep slopes with grassland; floodplains with grassland; oak-pine forest; 1613–2250 m.

Specimens examined:—CHIHUAHUA: 18 August 1998, 2 km S of Santo Tomas in the Barrio San Ignacio, ca. ½ km S of Rio Papigochic, R. Spellenberg 12692, L. Brouillet, T. K. Todsen (NY) . SONORA: 1851, Between the San Pedro and Sonoita rivers, C. Wright 1005 (fototype, CAS) ; 19 May 2010, Just south of New Mexico border, W side Animas, Valley, 54.2 km (by air) E of Agua Prieta, Cuenca Los Ojos Foundation property, T. R. Van Devender 2010-555, A. L. Reina G. (USON) ; 26 April 2009, Animas Valley, ca 57.9 km E of Agua Prietaa, Cuenca Los Ojos Conservation Area, A. L. Reina G. 2009-56, T. R. Van Devender, B. T. Wilder, J. L 20-V1987, Anderson (USON); 17 July 2001, 7.8 km NW of Santa Cruz on road to Nogales, A. L. Reina G. 2001-544, T. R. Van Devender (USON) ; 16 August 2001, 3 km north of Santa Cruz on road to Nogales, T. Van Devender 2001-707, A. L. Reina, J. Sánchez E. O. Gutiérrez, E. Gómez L. (MEXU 20 May 1987, 10 km al S de Cananea, Carretera a Arizpe, P. Tenorio L. 13559, C. Romero de T. (MEXU).