| | The genera of Cactaceae |
~ Strombocactus, cf. Hunt (1967)
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 plants vegetatively reduced almost entirely to rosettes of large, trigonous tubercles. The stems spiny; discoid to globose; 2.5–20(–30) cm in diameter; apically depressed to not apically depressed (flattened). The plants terrestrial and self supporting, or geophytic (barely rising above ground level); unbranched; erect; usually solitary; to 0.02–0.2(–0.3) m high. The stems not segmented; not ribbed and grooved. The plants very conspicuously tuberculate. The tubercles growded basally, 5–15 mm long, 7–15 mm wide basally, erect, rounded below, smooth, apically pointed. The tubercles not connected by ribs; spirally disposed. The areoles associated with tubercles; distant; spirally disposed; simple (at the tips of the tubercles); without glochids; with spines. The spines clustered; 3–4; 0.5–1.5 cm long; showing little or no difference between radials and centrals; somewhat flexible; straight, or curved (or slightly bent); whitish-brown. The mature stems leafless.
Flowering during the day. The flowers terminal; one per areole; funnelform; sessile; small to medium-sized; 1–2.5 cm long; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium; naked. The hypanthial tube naked; without scales; spineless. The perianth white and pink, or white and brown (the midveins coloured). The perianth segments numerous, narrow, pointed, spreading; elongate, relatively narrow to relatively short, broad; pointed. Stamens numerous 2; adnate to the perianth (inserted in the throat and tube).
The mature fruit 1.6–2.5 cm long; clavate; whitish brown; naked; without spines; without persistent floral remains; non-fleshy when mature; indehiscent. The seeds 0.7–1 mm long; black; pyriform; not encased in bony arils. The testa tuberculate. Cotyledons reduced or vestigial.
Natural Distribution. Mexico.
Classification. 1 species (O. denegrii). Subfamily Cactoideae. Tribe Cacteae.
Images. • obrego1.jpg.
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’.
