288. Astragalus petraeus Karelin & Kirilov, Bull. Soc. Imp. Naturalistes Moscou. 15: 333. 1842.
喜石黄耆 xi shi huang qi
Astragalus irkeschtami B. Fedtschenko; A. xylorrhizus Bunge.
Plants 5-30 cm tall, vegetative parts covered with ± medifixed, appressed hairs 0.6-1 mm. Stems several, 1.5-7 cm, densely covered with mostly white hairs. Leaves 4-8 cm; stipules 3-4 mm, adnate to petiole for 1-2 mm, often shortly connate behind stem, white and black or only white hairy; petiole 1-2 cm, like rachis densely white hairy; leaflets in 4-7 pairs, 6-15 × 3-8 mm, both surfaces densely covered with appressed hairs ca. 1 mm. Racemes short, rather densely 10-18-flowered; peduncle 8-11 cm, densely covered with appressed white hairs, toward raceme increasingly black hairy; bracts ca. 2 mm, white and predominantly black hairy, at margins mainly with subbasifixed to basifixed hairs. Calyx 8-10 mm, densely covered with tangled, spreading or ascending, extremely asymmetrically bifurcate to subbasifixed, white hairs up to 1 mm and especially on abaxial side with shorter, more symmetrically bifurcate, black hairs; teeth 2-3 mm. Petals violet; standard obovate, 18-22 × ca. 7 mm, constricted below middle, apex emarginate; wings 17-20 mm; keel 14-17 mm. Legumes sessile, pendulous, distinctly upcurved-falcate, 20-30 mm, 2-3 mm thick, apex shortly acuminate; valves densely covered with spreading or ascending, extremely asymmetrically bifurcate to subbasifixed, white hairs up to 1 mm and especially on adaxial side with shorter, more symmetrically bifurcate, black hairs.
Desertic mountain slopes; 2800-3200 m. Xinjiang [Kazakhstan, Kyrgyzstan].