| | The genera of Cactaceae |
The plants succulent; condensed-cactoid; low and very compacted in their entirety. The stems spiny to not spiny (the spines ephemeral); more or less globose, or barrel-shaped to shortly cylindric (the apex woolly); somewhat apically depressed; cephaliate (at least, the apex woolly). The plants lithophytic (growing on steep limestone and gypsum cliffs); erect; solitary, or clustering; to 0.08–0.12 m high (to 10 cm in diameter). The stems not segmented; deeply grooved, conspicuously 6–15 ribbed and grooved (often with smaller riblets between). The ribs longitudinal. The plants not conspicuously tuberculate. The areoles not tubercle-associated; borne in longitudinal series (along the ribs); numerous and close-set, simple. The flowering areoles differing in form from the non-flowering ones (being woolly). The areoles at first with spines. The spines solitary, or paired, or clustered; 1–3; showing little or no difference between radials and centrals; twisted, straight, or curved. The mature stems leafless.
Flowering during the day. The flowers terminal; one per areole; widely campanulate, or bowl-shaped; sessile; small to medium-sized; 0.7–3 cm in diameter; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium. The hypanthial tube slender, naked. The perianth white and orange, or red (or magenta). The perianth segments relatively short, broad; slightly apiculate, or blunt.
The mature fruit slightly ellipsoidal, or globose; naked; non-fleshy when mature; dry when mature, indehiscent. The seeds to 1 mm long; brown to black; not encased in bony arils; with a strophiole obscuring the hilum. The testa shiny; tuberculate. Cotyledons reduced or vestigial.
Natural Distribution. Mexico.
Classification. 2 species. Subfamily Cactoideae. Tribe Cacteae.
Cf. Hunt, 1967.
Images. • Aztekium hintonii: © Zoya Akulova (2013). • Aztekium hintomii: © Zoya Akulova (2013).
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’.
