6. Astragalus arizonicus A. Gray, Proc. Amer. Acad. Arts 7: 398. 1868

Type: — USA, “ Arizona, near Camp Grant, Pinal County, April, Edward Palmer 53 (holotype: GH digital image 00058653!; isotype MO 022482!)

Tragacantha arizonica (A. Gray) Kuntze, Rev. Gen. 943. 1891. — Hamosa arizonica (A. Gray) Rydb., Bull. Torrey Bot. Club 54: 22. 1927.

Perennial but of short duration or annual. Stems thin, prostrate or decumbent, distally ascendant, up to 50 cm long, strigose to canescent, the trichomes dolabriform (joined at one point, before the base, forming a “t” with the arms of equal or different size). Stipules 2–4.5 mm long, semi-clasping, not connate, papery, triangular. Leaves 2–10 cm long; leaflets 5–17, 1.2–25 mm long, linear, oblong to ovate, mucronate. Peduncles 1–15 cm long, straight or curved, humistrate with age, the racemes 1.3–10 cm long, flowers 7–30. Flowers rose, lavender, blue, blue with white center, purple, white with pink, rose-purple to white, even greenish-buff with maroon lines, the banner with blue margins, sometimes red-violet veined, keel apex with blue-violet tones, sometimes fading indigo blue; the calyx 4.5–7 × 2–3.1 mm, minute strigose, the tube campanulate or cylindric, 3.2–4.1 mm long, the teeth 1.2–3 mm long, lanceolate to triangular; the banner 8–12 × 6–9.1 mm, recurved, obovate to suborbicular, scarcely retuse; the wings 6.7–10 × 1.7–2.5 mm, oblanceolate, the claw 2.4–4.3 mm long, the blade 4.7–6.5 mm long; the keel 8–10.4 × 2.2–2.7 mm, strongly incurved, the claw, 2.6–4.4 mm long, the blade 4.6–6.5 mm long. Pod 15–30 × 2.2–4 mm, ascendant, straight, linearoblong, laterally compressed, narrow at both ends, triquetrous (triangular in cross-section), ventrally carinate, laterally convex, grooved or flattened longitudinally dorsally, the valves thin, densely appressed, tiny strigose, papery, tan, purple to brown-purple, reticulate, with a internal complete septum or almost so; ovuels 13–22; seeds 4-angular, mitten-shapped, 1.8–3 mm long, brown, light-brown or light-green, sometimes with purple tones.

Distribution:— In Mexico recorded only at northern Sonora (Santa Cruz, Caborca, Pitiquito, Santa Ana, Magdalena Quino, Cucurpe, Santa Cruz, Imuris and Benajmín Hill), also in Arizona (USA) (Fig. 3).

Habitat:— Frequent on clay soils, rocky slopes, disturbed sites, roadsides, roadbanks; grasslands; mesquite areas; mountain slopes; stony slopes; grassy hills; lovegrass-mezquite; desert grassland; desert scrub with creosote bush, Yoshua tree, mesquite, prickle pear, oaks and juniper; forests associated with Yosua tree and Fouquieria, sometimes in bushes along roads; Yosua tree-ocotillo-oak-juniper association; riparian association; Sonoran desertscrub; next to river; 800–1000 m.

Comments:— Two other species with dolabriform pubescence distributes in that area, they are A. humistratus var. sonorae (with connated stipules and curved fruits) and A. amphioxys (calyx and petals larger and also with wider pods).

Specimens examined:—SONORA: 7 April 2010, Rancho El Aribabi, Mpio. Ímuris, cañón El Cajoncito en la intersección con el Río Cocóspera, D. A. Delgado; 9 April 1977, 17.2 miles south-southeast of Magdalena; palm canyon in Cerro Cinta de Plata (Sierra Babiso), T. R. Van Devender 3048, M. C. Kearns, K. L. Cole (NY); 8 March 2003, Reservoir El Yeso, ca. 6.5 km southeast of Magdalena, north of SON 54 (to Curcurpe), T. R. Van Devender 2003-155, A. L. Reina G. (MEXU, NY, USON); 28 March 1970, Ca. 5 mi from Magdalena along road to Cucurpe, L. McGill 6487, D. J. Pinkava, E. Lehto (NY); 4 May 1932, 15 mi. N Magdalena, F. R. Fosberg 7711 (CAS, NY); 14 April 1970, 4 mi NE of Magdalena on Hwy 15, Wm. F. Mahler 6086, J. W. Thieret (NY); 8–9 April 1977, 17.2 miles south-southeast of Magdalena; palm canyon in Cerro Cinta de Plata (Sierra Babiso), T. R. Van Devender s/n (NY, TEXLL), 21 April 1973, 17.2 mi. S. of Magdalena on road to Cucurpe, R. & M Spellenberg 3048. M. Spellenberg (NY); 22 March 1934, Nine miles north of Magdalena on Hermosillo, Nogales Highway, R. S. Ferris 8789 (CAS, NY, US); 24 March 1934, Nine miles north of Magdalena on Hermosillo, Nogales Highway, R. S. Ferris 8798 (NY); 5 May 1932; 8 March 1936, District of Altar, 7 mi. S. of Sasabe, D. D. Keck 3972 (CAS, US); 8 March 2003,, Reservoir El Yeso, ca. 6.5 km southeast of Magdalena, north of SON 54 (to Curcurpe), T. R. Van Devender 2003-144, A. L. Reina G. (NY); 24 April 2005, 9.4 km west-northwest of Rancho El Diamante, 2.6 km from Rancho Esmeralda (= Rancho Las Borregas), Sierra Las Avispas, A. L. Reina 2005-685, T. R. Van Devender, M. Schieber and M. Klotz (NY); 10 April 1998, Imuris, 9.2 km north of turn off to Magdalena on Mex. 15, A. L. Reina G. 98-425, T. R. Van Devender (MEXU, USON); 11 May 2006, Rancho El Aribabi, cruce del río Cocóspera, a 200 m al sur de la casa del rancho, J. J. Sánchez E. 06-046, E. Gómez L., E. Fernández (USON); 6 May 2005, Chula Vista ca. 35 km by air west of El Sásabe, A. L. Reina G. 2005- 808, T. R. Van Devender, A. Flesch, S. Jacobs (USON).