| | The genera of Cactaceae |
Fish-hook cactus, Hedgehog cactus. ~ Thelocactus, cf. Hunt (1967)
Including Ancistrocactus Britton & Rose, Coloradoa Boissev. & C. Davidson, Glandulicactus Backeb., Toumeya Britton & Rose
The plants condensed-cactoid; low and very compacted in their entirety. The plants’ appearance dominated by crowded interlacing areolar structures obscuring any tubercles, ribs or furrows, or dominated neither by crowded areolar structures nor by tubercles covering the areoles. The stems very spiny (with more or less interlacing spines); small, discoid, or globose, or ovoid, or shortly cylindric; (1–)2–9(–15) cm in diameter; ocasionally flat topped, but not apically depressed; neither cephaliate nor pseudocephaliate. The plants terrestrial and self supporting; unbranched (mostly), or offsetting; erect; solitary (mostly), or clustering (occasionally); to (0.01–)0.02–0.27(–0.4) m high. The stems not segmented; ribbed and grooved to not ribbed and grooved. The ribs 10–17; borne spirally, or borne spirally and longitudinal (sometimes straightening below). The plants conspicuously tuberculate. The tubercles longitudinally grooved adaxially from the areole towards their ‘axils’. The tubercular groove short, extending less than halfway to the ‘axil’. The tubercles connected by the ribs to not connected by ribs; spirally disposed (initially), or borne in longitudinal series. The areoles associated with tubercles, or not tubercle-associated; relatively distant. The components of adjacent areoles commonly so extensively covering the mature plant body as to obscure any ribs or furrows, or not obscuring details of the plant body. The areoles mostly spirally disposed. The morphologically geminate, super-imposed buds very close, forming single areoles. The areoles with the abaxial spine cluster at the tubercle tip connected to the adaxial floriferous meristem nearer its axil by a recessed linear isthmus or a ridge (more or less extended beyond the spine-bearing part, the tubercular groove often with nectar glands); woolly (at first), or not woolly; with spines. The spines clustered; 2–20; 0.3–4.5(–8.5) cm long; with radials and centrals differentiated (the (0-)1–6 centrals to 9 cm long, the 2–11 radials to 6 cm). Central spines 0–11. Radial spines 2–18. The spines usually including some hooked members, or never hooked; straight and hooked, or curved and hooked, or straight, curved, and hooked (usually with one or more of the radials hooked). The mature stems leafless.
Flowering during the day. The flowers solitary to aggregated; terminal (arising near the stem tips); one per areole; campanulate, or funnelform to campanulate; sessile; medium-sized; (1–)2–6 cm long; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium; naked. The hypanthial tube naked; without scales; spineless. The perianth green, or white, or cream, or yellow, or red, or pink, or purple. The perianth segments relatively short, broad. Stamens not exserted.
The mature fruit in the small sample recorded, 0.6–1.5 cm long; ovoid, or ellipsoidal, or clavate, or barrel-shaped; usually not naked (scaly); without spines; with persistent floral remains; fleshy to non-fleshy when mature; dehiscent (by various means), or indehiscent; if dehiscent, "by various means". The seeds blackish brown to black; ovoid (? - "broadly oval"); keeled, or not keeled; not encased in bony arils. The testa shiny, or dull; with some surface patterning. Cotyledons reduced or vestigial.
Natural Distribution. North America and Mexico.
Classification. 14 species. Subfamily Cactoideae. Tribe Cacteae.
Images. • Sclerocactus whipplei, with Ferocactus hamatacanthus and F. latispinus: Britton & Rose (1922). • Sclerocactus scheeri (as Ancistrocactus), with Coryphantha cornifera, C. neo-mexicana (= ?), Cochemiea posgeleri: ritton & Rose (1923).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2018 onwards. The genera of Cactaceae: descriptions, illustrations, identification, and information retrieval. Version: 14th November 2021. delta-intkey.com’.
