Cyathula officinalis (English common names: Cyathula root, Radix Cyathula, Ox Knee, Chinese: Chuan Niu Xi), is a species of Cyathula native to the China (Guizhou, Hebei, Shanxi, Sichuan, Yunnan, Zhejiang) and Nepal. Herbs perennial, 50-100 cm tall. Stem erect, slightly quadrangular, much branched or strigose. Petiole 0.5-1.5 cm, densely strigose; leaf blade elliptic or narrowly elliptic, rarely obovate, 3-10 × 1.5-5.5 cm, abaxially densely strigose, adaxially long strigose, base cuneate or broadly cuneate, margin entire, apex acuminate. Flower clusters in terminal spikes, light green, nearly white when dried, 1-1.5 cm in diam. Bracts shiny, 4-5 mm, apex pointed or hooked. Tepals of perfect flowers lanceolate, 3-5 mm, apex acute, inner 3 slightly narrow. Filaments densely hairy at base; pseudostaminodes rectangular, 0.3-0.4 mm, dentate-lobed at apex. Ovary cylindric or obovoid, 1.3-1.8 mm; style ca. 1.5 mm. Utricles light yellow, ellipsoid or obovoid, 2-3 × 1-2 mm. Seeds shiny, ellipsoid, 1.5-2 mm, smooth.