Stems usually leaning southward in adulthood, depressed-spheric to ovoid-cylindric, 19-100(-300) × (20-)36-65(-100) cm. Ribs 20-30(-40), shallowly notched immediately above each areole. Spines 16-25(-29) per areole, central spines and larger radial spines dull pink, gray, or tan; smallest spines per areole white, slender, often bristlelike, less than 1 mm diam., strongly contrasting with central spines; central spines (1-)2-4, often with several, subulate subcentral spines, rigid; principal central spine strongly hooked (very rarely straight), 36-120(-150) mm from curve of hook to base of spine, 1.5-4(-7) mm wide, strongly annulate, terete, ± angular, or flattened and often adaxially troughlike; other central spines subulate, slightly smaller. Flowers similar in color inside and out, 4-8.5 × 4-6.5 cm; inner tepals orange, red, or yellow with orange to red midstripes, or wholly yellow; stigma lobes yellow, orange, or red. Fruits ± readily dehiscent through basal pore, bright yellow, 35-60 × 18-40 mm, thick walled, leathery or fleshy, locule dry, hollow except for seeds. Seeds (1.9-)2-2.5(-2.9) mm, essentially smooth with very narrow and slightly raised reticulations. 2n = 22. Flowering late summer(-fall). Desert scrub, grasslands, south-facing slopes in lower edges of oak woodlands, flats, bajadas, mountainsides, usually relatively deep soils of limestone and igneous origin; 100-1600(-1800) m; Ariz., N.Mex., Tex.; Mexico (Chihuahua, Sonora). The stems of Ferocactus wislizeni commonly lean southward, hence the vernacular name, compass barrel. Eventually they fall to the ground from their own weight, uprooting themselves. Introgressive hybridization with Ferocactus cylindraceus is thus far not documented, but is often invoked as an explanation for difficulty in identifying individual specimens in or near the wide region of sympatry. The putative hybrids mostly vanish with sufficient expertise in identifying the 'parental' species.
Ferocactus wislizeni barely extends into Mexico, where two allopatric species, F. tiburonensis (G. E. Lindsay) Backeberg and F. herrerae J. G. Ortega, often are cited as varieties of F. wislizeni. All reports of intermediates with F. herrerae are based on normal F. herrerae, the subtropical species (R. S. Felger 2000).
The finely reticulate seed coat of Ferocactus wislizeni is diagnostic among the species of Ferocactus in the flora.
Benson 1982, FNA 2003
Common Name: candy barrelcactus Duration: Perennial Protected Status: No status in Arizona. General: Barrel cactus that is about as tall as wide, clearly a columnar plant with 20-28 ribs that are not markedly tuberculate. Spines: Hooked central spines obscure the stem, while the central spines are red but have a surface layer that is ashy gray with 4 per areole and forming cross, not flattened against the stem, these are strongly cross ribbed and 3-8 cm long. The radial spines are ashy gray with mostly 12-20 per areole, spreading and curling irregularly back and forth, but not cross ribbed. Flowers: Flower 4.5-6 cm diameter and 5-7.5 cm long, they can be orange, yellow or reddish and cup shaped with perianth parts which are narrowly lanceolate and apically sharply acute and mucronate while being borne on the crowns of the stem with a distinct purplish middle stripe. Fruits: Yellow and barrel shaped, they are fleshy and covered by numerous almost circular but shallowly fimbriate scales that are readily dehiscent through basal pore. Ecology: Found on deep soils of igneous and limestone origin, sandy desert soils, gravelly slopes, wash margins, alluvial fans, lower edges of oak woodlands and grasslands from 1,000-4,500 ft (305-1372 m), flowers July-September. Notes: The primary species of barrel cactus in the region, distinguished by being to 1 m tall, the flattened, hooked spines and showy yellow fruits at the apex. Called the compass cactus because it tends to lean south toward sun, species can live up to 100 years. Spines are said to cripple a horse unless they are treated the same day. Ethnobotany: The top of the cactus was lopped off and the interior pulp was crushed as a source of water in extreme circumstances; the seeds were parched, ground, and boiled into a mush; the spines were used as fish hooks by the Pima, and the fruit was made into a candy. Etymology: Ferocactus from Latin ferus, fierce and cactus referring to spines, while wislizeni is named after Frederick Adolf Wislizenus (1810-1889) an Army surgeon, explorer, and botanist. Synonyms: Echinocactus wislizeni Editor: SBuckley 2010, FSCoburn 2015