Description from Flora of China
Orobus humilis Seringe in Candolle, Prodr. 2: 378. 1825; Lathyrus altaicus Ledebour.
Herbs perennial, 20-30 cm tall. Stem slender, erect, sometimes branching, puberulent, wingless. Leaves paripinnate; tendril weakly branched or simple; stipules foliose, semisagittate, 10-16 mm, dentate; leaflets (2 or)3- or 4-paired, ovate or elliptic, 15-30(-50) × 10-20 mm, glabrous or abaxially puberulent, with reticulate veins. Raceme shorter than leaf, 2-5-flowered. Calyx campanulate; longest tooth ca. 1/2 length of tube. Corolla purple-red, 1.5-2 cm; standard orbicular, with claw; wings and keels auriculate at base. Ovary linear, glabrous. Legume linear, 4.3-5 cm. Seeds red-brown, elliptic, smooth. Fl. May-Jul, fr. Aug-Sep.
Forest margins, scrub forests, hill grasslands; below 2500 m. Gansu, Hebei, Heilongjiang, Jilin, Liaoning, Nei Mongol, Shanxi, Xinjiang [Korea, Mongolia, Russia].