A gynodioecious hexaploid (n  =  33), Cylindropuntia chuckwallensis M. A. Baker & M. A. Cloud-Hughes, is newly described. Populations of C. chuckwallensis extend from the Eagle Mountains of Joshua Tree National Park, through the Chuckwalla Mountains of Riverside County, to the north side of the Chocolate Mountains in Imperial County, California, USA, and occur on a variety of substrates primarily between 400–1600 m (1312–5250 ft) elevation. Of the flowering individuals studied, 38% produced only pollen-sterile flowers. Flower color in C. chuckwallensis ranges from dark red-purple (33%) through orange (54%) to yellow (13%). For most individuals (93%) the style and filaments are dark red to light pink. Morphological measurements were made for 15 populations of Cylindropuntia, including four of C. chuckwallensis, four of C. echinocarpa, three of C. multigeniculata, and four of C. acanthocarpa. Multivariate analyses indicated that C. chuckwallensis possesses a unique combination of characters. Fewer than 3% of the 121 C. chuckwallensis individuals sampled were misclassified by discriminate function analysis, one as C. echinocarpa, and three as C. multigeniculata.