Chromosome numbers are determined for 514 individuals belonging to 119 taxa within Cactaceae. Nineteen taxa have chromosome numbers reported for the first time. Based on geographic, morphological, and cytological data, three new nomenclatural combinations are made: Cylindropuntia ×cardenche (GRIFFITHS) PINKAVA & M. A. BAKER, Cylindropuntia imbricata (HAWORTH) F.M.KNUTH var spinitecta (GRIFFITHS) M.A.BAKER, and Echinocereus bonkerae THORNBER & BONKER ssp apachensis (W.BLUM & RUTOW) A.D.ZIMMERMAN. Four species are here newly published as interspecific hybrids based, in part, on several character states intermediate of their respective sympatric putative parents: Cylindropuntia ×cardenche (GRIFFITHS) PINKAVA & M.A.BAKER (pro. sp) comb. nov., Cylindropuntia ×pallida (ROSE) F.M.KNUTH (pro. sp), Opuntia ×charlestonensis CLOKEY (pro. sp), and Opuntia streptacantha LEMAIRE × O. tomentosa SALM-DYCK.