Abstract:The concept and delimitation of Actaea simplex (= Cimicifuga simplex) in the Ranunculaceae have been previously widely misunderstood in China owing to incomplete knowledge of its diagnostic characters. It has often been confused with the traditionally broadly defined “C. foetida”. Based on observations of herbarium specimens and living plants in wild populations, here we re-evaluate the variation pattern and taxonomic value of some morphological characters of the species, such as the flowering sequence of racemes on the inflorescence, flower color, and carpel stipe length, etc., which have all been neglected or ignored by Chinese taxonomists. Our results demonstrate that A. simplex is very readily distinguishable from its congeners by the terminal leaflets lanceolate to elliptic, often deeply 3-partite with the central partition pinnately 3-5-lobate, the terminal racemes elongate, flowering earlier than the often much shorter lateral racemes, the flowers white, the staminodes also white, cup-shaped, apex deeply bifid, and the carpels long stipitate with the stipes more or less elongate after anthesis. The species is revealed to be much more widely distributed in China than documented before, occurring in Anhui, Chongqing, Gansu, Guangdong, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Jiangxi, Jilin, Liaoning, Nei Mongol, Shaanxi, Shanxi, Sichuan, Yunnan, and Zhejiang.