Agave asperrima subsp. maderensis (Gentry) B. Ullrich Agave asperrima subsp. maderensis (Gentry) B. Ullrich in Sida 15: 254. 1992 sec. Espejo-Serna 2012=Agave scabra subsp. maderensis Gentry, Agaves Cont. N. Amer.: 300, f. 12.1, 12.4, 12.23, 12.24, t. 12.1. 1982 syn. sec. ???