Phytologia 63: 157. 1987.
Plants 16–30-branched, forming clumps. Stems erect to ascending, cylindric or somewhat tapering distally, 20–30(–70) × (4–)6–9 cm; ribs 10–13, crests slightly undulate; areoles 15–25 mm apart. Spines 13–16 per areole, usually straight, divergent-porrect, pale translucent yellow; radial spines 8–12 per areole, 5–25 mm; central spines 4–6(–8) per areole, 30–72 mm, abaxial central spine usually descending, paler than other central spines, often fading whitish, somewhat flattened. Flowers 4–6 × 5–7 cm; flower tube 18–25 × 12–30 mm; flower tube hairs 1 mm; inner tepals usually pale pink with midstripes slightly darker, proximal 1/3 greenish, 30–40 × 5–10 mm, tips relatively thin and delicate; anthers yellow; nectar chamber to 7 mm. Fruits green, becoming bronze where exposed to sun, 23–34 mm, pulp white. 2n = 22.
Phenology: Flowering Mar–Apr; fruiting Jun.
Habitat: Arizona Upland Subdivision of Sonoran Desert, exposed slopes, bajadas, hills, mountains, desert scrub, igneous and sedimentary substrates
Elevation: 300-900 m
Ariz., Mexico (Sonora).
Although it was initially considered a variety of Echinocereus engelmannii, E. nicholii differs in chromosome number and a suite of morphologic characteristics. With its non-erumpent flower buds, diploid chromosome number, relatively small and usually pale flowers, green fruits, and exclusively yellow spines, E. nicholii more closely resembles E. ledingii than E. engelmannii.