12. Rheum officinale Baillon, Adansonia. 10: 246. 1871.
药用大黄 yao yong da huang
Herbs large, 1.5-2 m tall. Rhizomes and roots stout. Stem stout, hollow, finely sulcate, with white hairs, especially above and at nodes. Petiole of basal leaf terete, ca. as long as blade or slightly shorter, pubescent; leaf blade orbicular, rarely broadly ovate, large, 30-50 cm in diam., or longer than wide, abaxially pubescent, adaxially glabrous, rarely pubescent along veins, basal veins 5-7, base subcordate; palmatilobate, apex subacute. Stem leaves smaller upward; ocrea large, to 15 cm, broad, outside with dense hairs. Panicles large; branches spreading. Pedicel 3-3.5 mm, slender, jointed below middle. Flowers 4- or 5-fascicled. Tepals 6, green to yellow-white, elliptic or narrowly elliptic, 2-2.5 × 1.2-1.5 mm. Stamens shorter than perianth. Style deflexed; stigma inflated. Fruit oblong-ellipsoid, 8-10 × 7-9 mm; wings ca. 3 mm wide, with longitudinal veins near margin. Seeds broadly ovoid. Fl. May-Jun, fr. Aug-Sep.
* Hills, forests; 1200-4000 m. ?Fujian, Guizhou, SW Henan, W Hubei, Shaanxi, Sichuan, Yunnan.
The roots and rhizomes used medicinally.