Monographs Details: Astragalus purshii var. pumilio 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:Variety Description - Dwarf, acaulescent or nearly so; leaves 2-5.5 (7) cm. long, with (7) 9-15 (17) oval or elliptic, obtuse or acute leaflets 3-8 mm. long; racemes loosely (2) 3-6-flowered, the axis 4-17 mm. long in fruit; calyx 8.6-12.6 mm. long, the cylindric or cylindro-campanulate tube 6.5-9 mm. long, 2.9-3.8 mm. in diameter, the teeth 2.1-4 mm. long; petals pink-purple; banner 16-18 (20.5) mm. long, 6.6—9 mm. wide; wings 15.3-18 (19) mm. long, the claws 7.3-8.7 (10.8) mm., the blades 7.7-9.5 mm. long, 1.8-2.7 mm. wide; keel (12) 13-15 (15.3) mm. long, the claws 7.4-8.6 mm., the blades 5.3-6.5 mm. long, 2.2-2.9 mm wide; pod obliquely ovoid-acuminate, 8—15 mm. long, 3.5—7.5 mm. in diameter, nearly straight and deeply groved ventrally in the lower ½, thence abruptly incurved through 90° or more into the deltoid or lance-triangular beak, the valves shaggy-villous with hairs up to 1.6-2.2 mm. long; ovules 17-21; seeds 1.6-2.5 mm. long.

Distribution and Ecology - Dry gravelly flats and hillsides, with piñon and sagebrush, 5500—6800 feet, locally plentiful in the foothills and on the lower slopes of the Desatoya, Shoshone, and Toiyabe Ranges, northwestern Nye and adjoining Churchill and Lander Counties, and of the West Humboldt Mountains, Pershing County, Nevada.— Map No. 87.—May and June.

Discussion:The present variety was described from a meager sample but has become much better known in recent years. In the Toiyabe Mountains the Pursh milk-vetch is represented also by populations of var. Purshii and var. tinctus, but these have larger flowers than var. pumilio and larger pods not or scarcely sulcate ventrally. The pod of var. pumilio resembles that of var. glareosus reduced in size, and fruits are required to separate it from the smaller-flowered phases of var. tinctus.
Distribution:Nevada United States of America North America|