Monographs Details: Astragalus mollissimus var. nitens Barneby
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(2): 597-1188.
Description:Latin Diagnosis - var. irolano arete affinis, foliis pube appressa argentea sericeo-canis nec hirsuto-tomentulosis, legumine striguloso nec hirsutulo absimilis.
Variety Description - Habit of var. Earlei, shortly caulescent, the stems up to 1 dm. long, the herbage satiny-canescent with appressed and a few longer, very narrowly ascending hairs up to 0.8-1.2 mm. long, the vesture tarnishing in age; stipules up to 1 cm. long; leaves 5-16 cm. long, with 21-31 oblong-oblanceolate or elliptic, obtuse or subacute leaflets 7-20 mm. long; peduncles (3) 5—10 cm. long; racemes 15-30- flowered, the axis 5-10 cm. long in fruit; calyx 9.3-11.6 mm. long, densely white- silky, the tube 5.8-6.4 mm. long, 3-3.5 mm. in diameter, the teeth 3.1—5.3 mm. long; petals apparently purplish; banner 15.3-16 mm. long, 5-6 mm. wide; wings 14.2-15 mm. long, the claws 6.8-7.4 mm., the blades 8.5-9.2 mm. long, 1.8-2 mm. wide; keel 12-12.7 mm. long, the claws 6.8-7.3 mm., the blades 5.8-6.2 mm. long, 2.5-2.8 mm. wide; pod narrowly and obliquely ovoid, ± 1.1-1.4 cm. long, 3.5-4.5 mm. in diameter, a little incurved, contracted at apex into a short, unilocular beak, the valves strigulose with appressed hairs up to 0.4-0.6 mm. long; ovules ± 30.
Distribution and Ecology - Habitat not recorded, but to be sought on dry grassy or brushy hillsides, known only from southern Coahuila (Parras; Saltillo).—Map No. 97.—May and June.
Discussion:These two gatherings of Palmer’s pioneer collection in southern Coahuila were referred by Watson (in Proc. Amer. Acad. 17: 342) to A. Humboldtii (= our var. irolanus below) from which they differ in the lustrous, almost silver-plated vesture of the leaves and the strigulose rather than hirsutulous or hirsute pod. The individual flower is that of var. irolanus, but the small, strigulose pod resembles that of var. Earlei, and var. nitens possibly represents no more than one of several minor variants transitional between its northern and southern relatives. Its status will remain uncertain until we can learn more of its habits and habitat.
Coahuila Mexico North America