Monographs Details: Astragalus lentiginosus var. coachellae Barneby
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
Family:Fabaceae
Description:Variety Description - Winter annual or short-lived perennial, densely strigulose-villosulous throughout with ascending or subappressed, nearly straight or wavy (and often some short, sinuous or curly) hairs up to 0.7-1 (1.2) mm. long, the herbage lustrously silvery-canescent, sometimes becoming greenish-cinereous in age; stems erect and ascending in clumps, (1) 1.5-3 dm. long; leaves 5-11.5 cm. long, with (7) 11-17 (21) broadly oval to obovate-cuneate, or oblong-elliptic, emarginate or obtuse and apiculate, flat or loosely folded leaflets 5-15 (17) mm. long; peduncles stout, erect, 3.5-8 cm. long; racemes loosely 11-25-flowered, the axis (3) 4-10 cm. long in fruit; calyx 6.6-7.8 mm. long, densely villosulous with white (and nearly always a few black or fuscous) hairs, the tube 4.5-5.3 mm. long, 2.7-3.2 mm. in diameter, the teeth 1.7-2.9 mm. long; petals pink-purple, the color quickly fading; banner 12.7-14.5 mm. long; wings (about 1 mm. shorter) 11.8-13.5 mm., the claws 4.7-5.9 mm., the blades 7.8-8.8 mm. long, 2.5-3 mm. wide; keel (0.7-1.8 mm. shorter than the wings) 10.8-11.6 mm. long, the claws 5-5.7 mm., the blades 6.3-6.8 mm. long, 3-3.4 mm. wide; pod broadly and obliquely ovoid-acuminate, greatly inflated, 1.6-2.1 cm. long, 0.9-1.4 cm. in diameter, broadly rounded at base, abruptly contracted into an erect or slightly incurved, unilocular beak ± 3.5-6 mm. long, the stiffly papery valves nearly always mottled, canescently strigulose, the complete septum 3.5—6 mm. wide; ovules 24—30.

Distribution and Ecology - Sandy flats, washes, outwash fans, sometimes on dunes, locally plentiful in the Larrea belt from 20 feet below to 1200 feet above sea level around Coachella Valley, from the north end of Salton Sea to the base of Morongo and San Gorgonio Passes (and collected once near the head of the latter, near Banning, ± 2300 feet), interior Riverside County, California.—Map No. 132.—February to May.

Discussion:

The combination of silvery foliage with lively purple flowers, these followed by swollen, mottled but at the same time gray-downy pods, makes var. coachellae one of the handsomest forms of the freckled milk-vetch. It is probably a southern offshoot of the polymorphic var. variabilis, of which the uncommon phases with foliage equally silky may be distinguished by their short calyx-teeth and slightly smaller flowers. The variety is apparently confined to Coachella Valley, where it is sometimes associated on dunes with A. Crotalariae, a species with much longer flower and a pod inflated but unilocular.

The var. coachellae was apparently first identified with A. Coulteri Bth. by Jones, and in recent monographs and floristic works has been treated under that name (or equivalent combination). Gray (1864, p. 233) listed A. Coulteri as a doubtful species; he may have studied the holotypus after 1864, but apparently neither Jones nor Rydberg saw Coulter’s plant, a very characteristic specimen of A. lentiginosus var. borreganus. Coulter is known to have reached the mouth of the Gila River, and I conjecture that it was in that region that he encountered the species, locally abundant in rainy seasons over the sandy plains of the Yuma Desert.

Distribution:California United States of America North America|