Euphorbia bilobata Engelm. Euphorbia bilobata Engelm. in Rep. U.S. Mex. Bound., Bot. 2(1): 190. 1858 sec. Martínez-Gordillo & al. 2002=Zygophyllidium bilobatum (Engelm.) Standl. in Contr. U.S. Natl. Herb. 13(6): 199, 227. 1910 syn. sec. Martínez-Gordillo & al. 2006