Cobblestone Milkvetch

Xylophacos nudisiliquus (A. Nelson) Rydb. Bull. Torrey Club 52: 368. 1925.
Astragalus nudisiliquus A. Nelson, Bot. Gaz. 54: 410. 1912.
A cespitose perennial, with a much branched eaudex; stems very short, less than 1.5 dm. long; leaves 3-6 dm. long, spreading ; stipules lanceolate, 3-5 mm. long; leaflets 9-19, obovate, more or less densely white-villous, 5-10 mm. long, rounded at the apex; peduncles 2-4 cm. long; racemes 5-8-flowered ; bracts subulate, 3-5 mm. long; calyx whitevillous, the tube 9-10 mm. long, about 3 mm. broad, the teeth subulate, 2 mm. long; corolla ochroleucous or slightly tinged with purple; banner obovate, retuse; wings slightly shorter, the blade linear; keel-petals slightly shorter than the wings, the blade short and broad, strongly arched and rounded at the apex; pod 2-2.5 cm. long, 1 cm. thick, and 5 mm. wide, slightly sulcate on the upper suture, rather sparingly villous, strongly incurved above the middle; seeds obliquely reniform, 3 mm. long, 2 mm. broad.
Type locality: King Hill. Elmore County, Idaho. Distribution: Type locality and Malheur County. Oregon.