Echinocereus enneacanthus

Plants branched forming dense or lax clumps with 20-100(-500) branches, usually branching before flowering. Stems some-what lax often sprawling, longest stems sometimes prostrate, cylindric, 8-40(-100-) × 3.2-15 cm; ribs (6-)7-10(-12), crests essentially uninterrupted; areoles (11-)14-52 mm apart. Spines 6-14 per areole, straight or central spines slightly curved throughout their lengths, ± opaque, white, pale tan, or purplish gray, often extensively tipped or banded with brown; radial spines 5-10(-13) per areole, 9.5-40(-47) mm, usually less than ¹/2 as long as central spines; central spines 1-4(-5) per areole, all or mostly projecting, abaxial spine porrect or descending, frequently compressed or angular in cross section (sometimes sulcate, keeled, or striate), (12-)20-84(-96) mm. Flowers (4.5-)5-7.5 × 5-5.6(-9) cm; flower tube 10-30 × 10-22(-40) mm; flower tube hairs 1-2 mm; inner tepals pink or magenta, darkest proximally, 28-55 × 8-14(-20) mm, tips relatively thin and delicate; anthers yellow; nectar chamber 4-6 mm. Fruits pale yellow-green or dull reddish, 20-30 mm, pulp white or pale pink. 2n = 22.

The commonly recognized concept of Echinocereus enneacanthus var. enneacanthus (W. O. Moore 1967; D. Weniger 1970; L. D. Benson 1982) pertained to the small eastern var. brevispinus.