| | The genera of Cactaceae |
~ Mammillaria Haw.
The plants non-laticiferous; cerioid; low and very compacted in their entirety. The stems very spiny; shortly cylindric to elongate cylindric; to 7 cm in diameter. The plants branched, or branched to unbranched; without cladodes; erect, or prostrate and erect; solitary, or clustering (often forming several-stemmed clusters). The branches cylindrical; to 100 cm long; 7 cm in diameter. The stems not segmented; not ribbed and grooved. The plants conspicuously tuberculate. The tubercles neither grooved nor ridged adaxially. The tubercles not connected by ribs; spirally disposed. The areoles associated with tubercles; closely approximating. The components of adjacent areoles so extensively covering the mature plant body as to obscure any ribs or furrows, or not obscuring details of the plant body. The areoles spirally disposed; 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 (terminal on the tubercles). The spines clustered; (9–)13–35; 0.5–5 cm long; with radials and centrals differentiated. Central spines 1–5. Radial spines 7–30. The spines usually including some hooked members (the centrals, the radials straight); straight and hooked. The mature stems leafless.
Flowering during the day. Pollination ornithophilous (pollinated by Hummingbirds). The flowers lateral (arising from the bases of older areoles, but sometimes forming rings around the stem tips); one per areole; narrowly funnelform; bilaterally symmetrical; sessile; medium-sized to large; 2.5–5.5 cm long; very irregular (with an oblique perianth). The receptacle conspicuously produced beyond the ovary into a tubular hypanthium to scarcely produced beyond the ovary (the tube short); naked. The hypanthial tube often bent into an S shape, or not S-shaped (?); naked. The perianth red. The perianth segments narrowly spreading; fairly elongate, relatively narrow; pointed. Stamens numerous.
The mature fruit globose, ovoid or clavate, 1.3–3 cm long (where recorded ...); red to purple (-ish); naked; fleshy (?); indehiscent. The seeds black; with perisperm (?); not encased in bony arils; with a strophiole obscuring the hilum, or without a strophiole hiding the hilum (?). The testa deeply pitted. Cotyledons reduced or vestigial.
General anatomy. Laticifers without laticifers.
Natural Distribution. Mexico.
Classification. About 4–5 species. Subfamily Cactoideae. Tribe Cacteae.
Cf. Anderson (2001).
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’.
