阿尔泰大黄 a er tai da huang

Rheum rhaponticum Herder.

Herbs large, 50-100 cm tall. Stem erect, hollow, finely sulcate, glabrous. Petiole of basal leaf ca. as long as blade, slender, glabrous; leaf blade ovate-cordate or triangular-ovate, 15-30 × 13-22 cm, abaxially papilliferous or pubescent, adaxially glabrous, base cordate, margin slightly sinuolate, apex obtuse. Stem leaves 1-3, shortly or very shortly petiolate, smaller, sometimes ca. as long as wide; ocrea brown, 3-6 cm, abaxially with very short hairs, clasping. Panicle narrowly ovate, large. Pedicel slender, jointed below middle. Flowers small, 4-7-fascicled. Tepals yellow-white, oblong or narrowly elliptic, inner 3 larger, ca. 1.5 × 1 mm. Stamens equal to perianth. Fruit oblong-ellipsoid, small, 5.5-7.5 × 4.5-6 mm, rarely retuse at both ends; wings narrow, 1-1.5 mm wide, with longitudinal veins at middle. Seeds black-brown, broadly ovoid. Fl. Jun-Jul, fr. Jul-Aug.

Forests, valleys; 1900-2400 m. N Xinjiang [Kazakhstan, Mongolia, Russia (Altay)].