| | The genera of Cactaceae |
~ ?Mammillaria, cf. Hunt (1967)
The plants condensed-cactoid; low and very compacted in their entirety. The stems spiny; globose, or shortly cylindric; 3–4 cm in diameter; not apically depressed. The plants offsetting; erect; low-growing, clustering; to 0.03–0.08 m high (?). The stems not segmented; not ribbed and grooved. The plants very conspicuously tuberculate. The tubercles relatively large, low, rhomboid, somewhat flattened, minutely dotted; neither grooved nor ridged adaxially. The tubercles not connected by ribs; spirally disposed. The areoles associated with tubercles; distant; spirally disposed. The morphologically geminate, super-imposed buds separated, with the lower one in the axil of the conspicuous tubercle that bears the upper one at its tip. The areoles distinctly bipartite, with the abaxial spine cluster at the tubercle tip and no recessed isthmus or other visible connection with the adaxial, floriferous meristem near its base; with spines (on the distal component). The spines clustered; 8–9; 0.4–1 cm long; with radials and centrals differentiated (the central spine 4–5 mm long, black or whitish with a dark tip, the radials 5–10 mm long, straight, radiating, whitish with dark tips). Central spines 1. Radial spines 7–8. The spines straight. The mature stems leafless.
Flowering during the day (?). The flowers terminal (arising from the axillary areolar components); one per areole; funnelform; sessile (?); small to medium-sized; 2–3 cm long (1.8–2.5 cm in diameter); regular. The receptacle scarcely produced beyond the ovary; not naked; without scales; spineless. The pericarpel woolly but lacking scales. The hypanthial tube not naked (cf. the pericarpel); without scales. The axils of the scales of the hypanthial tube not naked (woolly). The hypanthial tube spineless. The perianth yellow. The perianth segments relatively short, broad; pointed.
The mature fruit globose, or ovoid, or ellipsoidal; dull red; with persistent floral remains; non-fleshy when mature. The seeds with a large hilum, brown to black; globose or sub-globose; not encased in bony arils. Cotyledons reduced or vestigial.
Natural Distribution. Oaxaca, Mexico.
Classification. 1 species (O. macdougallii). Subfamily Cactoideae. Tribe Cacteae.
Images. • Ortegocactus macdougalii: © Zoya Akulova (2017).
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’.
