Slender Milkvetch

Microphacos gracilis (Nutt.) Rydb. Bull. Torrey Club 32:663. 1906.
Astragalus gracilis Nutt. Gen. 2: 100. 1818.
Astragalus microlobus A. Gray, Proc. Am. Acad. 6: 203. 1864.
Tragacanlha microloba Kuntze, Rev. Gen. 946. 1891.
Microphacos microlobus Rydb. Bull. Torrey Club 32: 663. 1906.
Astragalus parviflorus microlobus M. E. Jones, Rev. Astrag. 193. 1923.
A perennial, with a woody root; stems decumbent at the base or ascending, branched and flexuose, strigose-canescent, 2-5 dm. high; leaves mosdy spreading, 3-8 cm. long; stipules deltoid, 2-3 mm. long; leaflets 11-15, linear or oblong, 5-15 mm. long, 1-3 mm. wide, glabrous above, strigose beneath, rounded, truncate or retuse at the apex; peduncles 3-8 cm. long; racemes 4-8 cm. long; bracts lanceolate, 1 mm. long; calyx strigose, the tube 1.5 mm. long, the teeth deltoid, 0.5 mm. long; corolla purple, 7-S mm. long; banner obovate, strongly arched below the middle; wings obliquely obovate, falcate, with a rounded auricle, rounded at the apex; pod obliquely ovoid, cross-ribbed, grayish-strigose, 7-9 mm. long, 2.5 mm. wide, and 4 mm. thick, the upper suture acute, the lower concave, the cross-section reniform; seeds usually 2, brown, obliquely round-reniform, 2.5 mm. long.
Typk locality: " From White River to the mountains, on the plains of the Missouri " [South or North Dakota].
Distribution: South Dakota, Oklahoma, New Mexico, Utah, and Montana.