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| The genera of Cactaceae |
The plants laticiferous, or non-laticiferous (?); 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 very spiny; globose, or shortly cylindric. The plants unbranched, or branched (i.e., occasionally caespitose); erect; shrubby (suffrutescent from a thick rootstock, with a short stout basal trunk covered with withered tubercles); solitary, or clustering; to 0.2–0.35(–0.7) m high. The stems not segmented; not ribbed and grooved. The plants very conspicuously tuberculate. The tubercles 10–12 cm long, elongate, three-angled and resembling allioid leaves, apically areolate. The tubercles not connected by ribs; spirally disposed. The areoles conspicuously associated with tubercles; simple; not woolly; without glochids; with spines. The spines clustered; 6–16; 2–10 cm long; with radials and centrals differentiated (the centrals longer). Central spines 1–2. Radial spines 8–14. The spines flexible; flattened (papery, often twisted); yellowish. The mature stems leafless.
Flowering during the day. The flowers terminal (arising at the dorsal edges of young tubercles); one per areole, or more than one per areole (?); funnelform; short, 5–6 cm in diameter; sessile; to 8 cm long (and 5–6 cm in diameter); fragrant; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium. The pericarpel scaly. The hypanthial tube not naked; with scales (these short, apiculate). The axils of the scales of the hypanthial tube more or less naked. The hypanthial tube spineless. The perianth yellow. The perianth segments spreading; pointed. Stamens separated from the perianth by a conspicuous ring of hairs; not exserted.
The mature fruit to 3 cm long; ovoid to ellipsoidal; not naked (with persistent scales); without spines; with persistent floral remains; non-fleshy when mature. The seeds 2.4 mm long; brown to black; ovoid (? - "broadly oval"); not encased in bony arils. The testa minutely verrucose. Cotyledons reduced or vestigial.
General anatomy. Laticifers with laticifers (e.g., in L. principis), or without laticifers (?).
Natural Distribution. Northern and central Mexico.
Classification. 1 species (L. principis). Subfamily Cactoideae. Tribe Cacteae.
Cf. Hunt (1967).
Images. • Leuchtenbergia principis: Britton & Rose (1920). • Leuchtenbergia principis: Britton & Rose (1922).
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’.
