Desert barrel cactus, California barrel cactus

Echinocactus viridescens Torrey & A. Gray var. cylindraceus Engelmann, Amer. J. Sci. Arts, ser. 2, 14: 338. 1852; Ferocactus acanthodes (Lemaire) Britton & Rose var. eastwoodiae L. D. Benson; F. acanthodes var. lecontei (Engelmann) G. E. Lindsay; F. eastwoodiae (L. D. Benson) L. D. Benson

Stems straight, erect or nearly so (or leaning), cylindric, (20-)45-150(-300) × (20-)25-40(-50) cm; ribs (18-)21-31, shallowly notched immediately above each areole. Spines 12-32 per areole, central spines and larger radial spines whitish, yellow, pink, dull red, or brown; smallest spines per areole slender, sometimes bristlelike, less than 1 mm diam. (rarely absent); central spines 4 per areole, major rigid central spines surrounded by weaker subcentral spines; principal central spine moderately curved, sometimes twisted, usually not strongly hooked except on relatively young plants, annulate, adaxial surface usually flat or even concave, 36-140[-170] × 2-4.5 mm. Flowers maroon outside, yellow inside, 3-6 × 4-6 cm; inner tepals commonly yellow, (rarely with reddish midstripes, very rarely orange to red with a darker red midstripes); stigma lobes yellow (to red). Fruits ± readily dehiscent through basal pore, bright yellow (very rarely reddish), 30-40(-50) × 15-20 mm, leathery or fleshy, locule dry, hollow except for seeds. Seeds (1.5-)2-3 mm, pitted. 2n = 22.

Flowering early spring-early summer (late summer-early fall). Interior chaparral, Mojave desert scrub, Sonoran desert scrub, usually on rocky slopes, igneous and limestone substrates; 0-1500 m; Ariz., Calif., Nev., Utah; Mexico (Baja California, Sonora).

The name Ferocactus acanthodes has been widely applied to this species but was based on a small plant of unknown origin (and the original specimen lost), and is therefore ambiguous (N. P. Taylor 1979).

The vernacular name "compass barrel" is sometimes misapplied to Ferocactus cylindraceus , which grows straight up in its old age, instead of leaning as would F. wislizeni.

The varieties recognized by L. D. Benson (1982) are not consistently distinguishable.