Pachycereus in Contr. U.S. Natl. Herb. 12: 420. 1909 sec. Arias & Terrazas (2009)
- ≡Cereus subg. Pachycereus in Rep. (Annual) Missouri Bot. Gard. 16: 63. 1905 syn. sec. Arias & Terrazas (2009)
- Type: Pachycereus pringlei
- =Backebergia in Anales Inst. Biol. Univ. Nac. México 24: 230. 1954 syn. sec. Arias & Terrazas (2009)
- =Pterocereus in Ceiba 4: 135. 1954 syn. sec. Arias & Terrazas (2009)
- Type: Pterocereus foetidus
Phylogenetic studies based on morphological and molecular data show consistently that Pachycereus s.str. is a monophyletic group with five species (Arias & al. 2003; Arias & Terrazas 2006, 2009; Arias & al. 2012). Other species previously considered in Pachycereus (Buxbaum 1961; Gibson & Horak 1978; Anderson 2001; Hunt 2006; Nyffeler & Eggli 2010) have been transferred to Lemaireocereus, Lophocereus, and Pseudomitrocereus. More inclusive and robust new evidence may corroborate or refute the current delimitation of these last genera. Pachycereus s.str. includes tree-like species, interareolar grooves on the stems, abundant trichomes on flower, and flexible spines on the fruit. The genera Backebergia and Pterocereus (both of them monospecific) remain inconclusive on molecular data available (Arias & al. 2003; Hernández-Hernández 2011), therefore their recognition as separate genera remains premature. Recent monograph by Arias & Terrazas (2009).