Ralston & Hilsenbeck. 1992. Madroño, 39(4): 281–284.
Corynopuntia densispina forms an open mound of clavate cladodes, sometimes to 1.5 m across but often 30-50 cm; plants may be up to 30 cm tall. The stems are firmly attached. The cladodes grow from from lateral areoles. There are 7-11+ central spines. The primary radial spine pair (the most abaxial) is greater than half the length of the central. C. densispina is morphologically similar to the diploid C. aggeria. Additionally, in all known populations, C. densispina occurs sympatrically with C. aggeria but C. densispina is more abundant in lower-lying areas with high clay content. Hybrids between C. densispina and C. aggeria have been reported. C. densispina was long disregarded as a distinct species due to similarities with other C. schottii-complex plants. The most recent treatment is in Club Chollas of the Big Bend 3.0 (see Appendix E). C. densispina is tetraploid and has diffuse, thickened roots (not tuberous).