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| The genera of Cactaceae |
The plants somewhat succulent; more or less 'cactoid'; more or less cerioid, or opuntioid. The stems spiny. The plants branched and offsetting; clustering (and cushion forming); to 0.1–0.4 m high (low, forming rounded cushions 2–3 m wide). The branches to 1–3 cm long. The stems segmented, or not segmented; not ribbed and grooved. The plants not conspicuously tuberculate. The areoles not tubercle-associated; numerous; small, simple; silky- hairy; with spines. The spines solitary to paired, or clustered (usually); 1, or 2–3; 0.2–7.5 cm long; with radials and centrals differentiated to showing little or no difference between radials and centrals (variable regarding presence or absence of radials, the single central longer longer and stronger). Central spines 1. Radial spines when present, 1–2. The spines stiff, or flexible; straight, or curved; flattened, or terete; variously white, yellowish or brownish, flesh-coloured or becoming grey. The mature stems with well developed leaves and with much reduced leaves. Leaves of mature stems minute to small (2–10 mm long); fleshy; terete (cylindric to ovoid or globular, persistent). Laminae veined.
Flowering during the day. The flowers solitary; sub-terminal to terminal (terminating main branches and/or spur shoots, sometimes more or less continuous with the stem); one per areole; sessile; medium-sized; 3–5 cm long; regular to somewhat irregular. The receptacle not produced beyond the ovary; not naked; with scales (the lower leaflike, the upper sepaloid); with spines, or spineless. The perianth petaline; 20–100 (many); white, or yellow. The perianth segments relatively short, broad. Stamens 20–100 (numerous); adnate to the perianth (at its base); not exserted; not grouped. Gynoecium superior (? - short, with leaflike bracts). Locules without ‘false septa’. Placentation presumably parietal. The ovules in the single cavity 15–100 (numerous).
The mature fruit 2–6 cm long; sub- globose, or ellipsoidal to clavate; not naked (with numerous fleshy bracts in M. poepigii); spiny (in M. patagonica), or with glochids; with persistent floral remains; indehiscent. The seeds 3–4 mm long; almost circular, smooth to slightly tuberculate, shiny black; "almost circular"; not encased in bony arils. The testa sightly tuberculate, or smooth, without ornamentation. Cotyledons linear.
Physiology. C3.
Natural Distribution. Mostly at high altitudes in Chile, western Argentina and Patagonia, cold-resistant.
Classification. 2 species. Subfamily Maihuenioideae.
Cf. Hunt (1967).
Images. • Maihuenopsis glomerata: © Zoya Akulova (2007). • Maihuenopsis glomerata: © Zoya Akulova (2007). • Maihuenia patagonica (as brachydelphys and tehuelches) and M. poeppigii: Briton & Rose (1919).
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’.
