Rheum caspicum Pallas; R. songaricum Schrenk.

Herbs 35-50 cm tall. Roots stout. Stem erect, short, hollow, glabrous. Basal leaves procumbent, large; petiole short, subterete, glabrous; leaf blade cordate-orbicular or orbicular, usually slightly wider than long, 20-35 × 27-50 cm, papery, abaxially glabrous or papilliferous, base cordate, margin serrulate, apex obtuse. Stem leaves orbicular, small, 5-6 cm in diam. Panicle 3-branched at middle, glabrous or papilliferous above. Pedicel 2.5-5 mm, slender, jointed above middle. Flowers 1- or 2-fascicled; bracteole scale-like. Tepals yellow-white, broadly elliptic, ca. 2 × 1.5 mm, outer 3 smaller. Stamens slightly shorter than perianth. Anthers oblong; filaments inflated forward to base, ca. 1 mm; disk adnate to base of perianth. Ovary triangular-ovoid; style slender, reflexed; stigma discoid. Fruit purple-red, ovoid, sometimes triangular-ovoid or ovoid-ellipsoid, 1-1.2 cm × 6-9 mm, base cordate, apex retuse; wings narrow, ca. 1.5 mm wide, with longitudinal vein near margin. Seeds dark brown, ovoid, ca. 5 mm wide. Fl. May, fr. Jun-Jul.

Grasslands, deserts, plains; 500-1000 m. W Xinjiang [Afghanistan, Kazakhstan, Russia (European part)].