Rheum franzenbachii Münter; R. franzenbachii var. mongolium Münter; R. undulatum Linnaeus; R. undulatum var. longifolium C. Y. Cheng & T. C. Kao.

Herbs large, 50-150 cm tall. Stem stout, hollow, glabrous, or pilose at nodes. Petiole of basal leaf stout, usually shorter than blade, pubescent; leaf blade light green or dark purple-red abaxially, dark green adaxially, triangular-ovate, subovate, broadly cordate, or narrowly triangular, large, 12-40(-57) × 10-30(-61) cm, abaxially pubescent, adaxially glabrous or sparsely pubescent near veins, basal veins 5-7, base cordate, margin crispate or sinuate, apex obtuse or acute. Stem leaves smaller, triangular or ovate-triangular. Panicle large, jointed at lower part. Flowers 3-8-fascicled, 2.5-4 mm. Tepals 6, not spreading, white-green or yellow-white, outer 3 smaller, inner 3 very broad to orbicular, ca. 2 mm. Ovary broadly ellipsoid to oblong-ellipsoid; style short; stigma inflated. Fruit triangular-ovoid to oblong-ellipsoid; wings narrow, 1.5-2 mm. Seeds brown, ovoid or ovoid-ellipsoid, ca. 3 mm. Fl. Jun, fr. after Jul. 2n = 44.

Slopes; 1000-1600 m. Hebei, Heilongjiang, Hubei, Jilin, Nei Mongol, Shanxi [Mongolia, Russia (E Siberia); cultivated in Europe].