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| The genera of Cactaceae |
Top cactus. ~ Strombocactus, cf. Hunt (1967)
Including Gymnocactus Backeb., Normanbokea Kladiwa & Buxb., Rapicactus Buxb. & Oehme
The plants condensed-cactoid; low and very compacted in their entirety. The plants’ appearance dominated neither by crowded areolar structures nor by tubercles covering the areoles. The stems spiny; globose (mostly, to top-shaped), or shortly cylindric; (1–)2–9(–20) cm in diameter; apically depressed to not apically depressed. The plants terrestrial and self supporting; mostly unbranched, or offsetting; erect; solitary, or clustering; to 0.05–0.16 m high. The stems not segmented; ribbed and grooved, or not ribbed and grooved. The ribs when present, borne spirally. The plants conspicuously tuberculate. The tubercles mostly low but sometimes prominent and rounded or conical; 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. The areoles associated with tubercles (borne at their tips); distant; spirally disposed; 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; often woolly; without glochids; with spines. The spines solitary to clustered; 2–36(–50); 0.1–3 cm long; with radials and centrals differentiated, or showing little or no difference between radials and centrals (sometimes lacking centrals). Central spines 0–3(–5). Radial spines 1–20(–50). The spines usually flexible; never hooked. The mature stems leafless.
Flowering during the day. The flowers terminal; one per areole; shortly funnelform; sessile; small to medium-sized; 0.7–3.8 cm long; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium, or scarcely produced beyond the ovary (?). The pericarpel "naked or with only a few scales above". The hypanthial tube naked, or not naked; with scales, or without scales. The axils of the scales of the hypanthial tube if present, more or less naked. The hypanthial tube spineless. The perianth white, or yellow, or red, or pink, or purple. The perianth segments relatively short, broad; pointed, or apiculate. Stamens numerous; adnate to the perianth (inserted in the tube and throat).
The mature fruit 0.4–1.8 cm long; berrylike fleshy; dehiscent. The seeds 1–1.5 mm long; with a large hilum, black; not encased in bony arils. The testa verrucose. Cotyledons reduced or vestigial.
Natural Distribution. Northerm Mexico.
Classification. Subfamily Cactoideae. Tribe Cacteae.
Images. • Turbinicarpus pseudomacrochele subsp. kranzianus: © Zoya Akulova (2012). • Turbinocarpus pseudomacrochele: Zora Zakulova (2012).
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’.
