密序大黄 mi xu da huang

Rheum nutans Pallas.

Herbs large, ca. 1 m tall. Rhizomes and roots dark brown, stout. Stem erect, hollow, glabrous. Petiole of basal leaf subterete, shorter than or ca. as long as blade, muricate beneath; leaf blade ovate-cordate, rarely ovate, large, 20-30 cm in diam., sometimes slightly longer than wide, abaxially pubescent, adaxially glabrous, basal veins 5-7, base cordate, margin entire, apex obtuse. Stem leaves shorter petiolate, small; ocrea short, glabrous or slightly muricate. Panicle large, densely branched. Pedicel slender, jointed below middle. Flowers fascicled. Tepals yellow, elliptic, subequal, ca. 2 mm. Fruit broadly ellipsoid to oblong-ellipsoid, ca. 1.2 × 1.1 cm, both ends cordate; wings narrower than seeds, ca. 3 mm wide, with longitudinal veins at middle. Seeds dark brown, ovoid to broadly ovoid. Fl. Jun-Jul, fr. Aug. 2n = 22, 44.

Slopes; ca. 2000 m. N Xinjiang [Kazakhstan, Mongolia, Russia (Far East, Siberia)].