Osmorhiza berteroi is a species of flowering plant in the carrot family known by the common name mountain sweet cicely. It is native to much of western and northern North America, as well as Argentina and Chile, where it grows in wooded and forested areas. It is an aromatic perennial herb producing a branching stem which may exceed a meter tall. The plentiful green leaves have blades up to 20 centimeters long which are divided into three toothed or lobed leaflets. The blade is borne on a long petiole. The flower cluster is a compound umbel of many tiny white flowers at the tip of a stemlike peduncle. The narrow, elongated fruit is ribbed and bristly, measuring up to 2.5 centimeters long.