10. Echinocereus nicholii (L. D. Benson) B. D. Parfitt, Phytologia. 63: 157. 1987.
Nichol’s hedgehog cactus, golden hedgehog cactus
Echinocereus engelmannii (Parry ex Engelmann) Lemaire var. nicholii L. D. Benson, Proc. Calif. Acad. Sci., ser. 4, 25: 258, plate 25, fig. B. 1944
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.
Flowering Mar-Apr; fruiting Jun. Arizona Upland Subdivision of Sonoran Desert, exposed slopes, bajadas, hills, mountains, desert scrub, igneous and sedimentary substrates; 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.