Discocactus placentiformis (Lehm.) Schumann [ Discocactus tricornis Monv. ex Pfeiff. & Otto]
Discocactus placentiformis (Lehm.) Schumann [ Cactus placentiformis Lehm.] [Cactaceae]
L.K.G. Pfeiffer, F. Otto, Abbild. Beschr. Cact. (Coloured version), vol. 2 : p. 28, t. 28 (1839)