Dasylirion wheeleri var. durangense (Trel.) Laferr. Dasylirion wheeleri var. durangense (Trel.) Laferr. in Ann. Missouri Bot. Gard. 78 (2): 519-520, f. 2. 1991 sec. Espejo & López-Ferrari 1996≡Dasylirion durangense Trel. in Proc. Amer. Philos. Soc. 50: 438. 1911 syn. sec. ???