Perideridia erythrorhiza is a rare species of flowering plant in the carrot family known by the common names western yampah and redroot yampah. It is endemic to Oregon in the United States, where there are about 20 occurrences. The populations occur in three regions in southwestern Oregon which are separated by more than 50 miles. The three separate groups are located in the Klamath Mountains and on either side of the Cascade Range. Threats to this rare species include housing development, agriculture and grazing, herbicides, introduced species, and nickel mining.