Harrisia simpsonii Small ex Britton & Rose, Cactaceae 2: 152. 1920
Harrisia simpsonii, Cactaceae 2: 152. 1920
is basionym for Cereus gracilis var. simpsonii in Cact. Succ. J. (Los Angeles) 41: 126. 1969
is basionym for Harrisia gracilis var. simpsonii in Novon 14: 367. 2004
Lectotype (designated by Franck, A. R. 20161): USA. Florida, Monroe Co., Pumpkin Key, collected by Small in 1916, flowered 18 Jun 1917 [43933] (NY, isolectotype: US [00174217]).