Opuntia mamillata Schott ex Engelmann, Proc. Amer. Acad. Arts 3: 308. 1856; O. fulgida Engelmann var. mamillata (Schott ex Engelmann) J. M. Coulter

Stem segments appearing spineless or nearly so from afar, exposing strongly mammillate tubercles beneath. Spines of stems not or little interlaced with spines of adjacent areoles, longest usually 1-2 cm; sheaths tightly fitting. 2n = 22.

Flowering spring-fall (Apr-Aug, Oct). Sonoran desert scrub, sandy flats, rocky slopes, rolling hills; 200-1100 m; Ariz.; Mexico (Baja California, Sinaloa, Sonora).

A morphotype with crested stems from south-central Arizona is commonly cultivated as the boxing-glove cactus.