| | The genera of Cactaceae |
~ Opuntia, cf. Hunt (1967)
Including Corynopuntia F.M. Knuth, Marenopuntia Backbg., Micropuntia Daston
The plants succulent; opuntioid; low and very compacted in their entirety, or not ‘low and very compacted’. The stems very spiny. The plants terrestrial and self supporting; branched (with indefinite growth and many erect branches), or unbranched; without cladodes; erect; neither shrubby nor tree-like, or shrubby, or tree-like (low growing to mat- or cushion-forming, low bushes, sometimes clump forming or treelike, sometimes with large taproots); clustering (forming large colonies); to 0.03–1 m high. The main stem obovoid to more or less cylindrical. The branches elliptical- cylindrical, or clavate, or globose. The stems segmented; longitudinally 8–10 ribbed and grooved (the ribs sometimes), or not ribbed and grooved (Corynopuntia). The ribs 8–10; when present, longitudinal. The plants conspicuously tuberculate to not conspicuously tuberculate (only slightly so). The tubercles when present, connected by the ribs; borne in longitudinal series. The areoles associated with tubercles, or not tubercle-associated. 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 large simple; ostensibly without glochids (those of the stems being fugacious), or with glochids (towards the branch apices and on the ovary only); with spines (but sometimes confined to distal areoles). The spines clustered; (1–)5–25; 0.1–6(–7) cm long; showing little or no difference between radials and centrals; sheathed to without sheaths (the sheaths much reduced); basally roughened or bulbous, somewhat flattened. The mature stems with much reduced leaves. Leaves of mature stems fugacious, minute to small; fleshy; terete.
Flowering during the day. The flowers terminal (or both terminal and lateral); one per areole; sessile; medium-sized; 3–4 cm long; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium to scarcely produced beyond the ovary; not naked; with scales (?); with spines (and sometimes glochids), or spineless (then sometimes with glochids). The hypanthial tube bearing white woolly areoles, yellow glochids and often long, slender yellow spines; not naked; with scales (?); with spines (and sometimes glochids), or spineless (then sometimes with only glochids). The perianth sequentially intergrading from sepals to petals, or petaline, or of ‘tepals’; white, or yellow, or pink, or purple. The perianth segments relatively short, broad; blunt, or pointed, or apiculate. Stamens adnate to the perianth (inserted in the throat); not exserted. The funicles circinate.
The mature fruit 1.5–9 cm long; fleshy, or non-fleshy when mature; dehiscent, or indehiscent. The seeds 2.5–5 mm long; whitish to yellowish, the funicular girdle well developed, the funicular envelopes glabrous or covered with thin trichomes; conspicuously hairy, or not hairy; with perisperm (this large); encased in their bony arils. Cotyledons fleshy, foliaceous.
Natural Distribution. Mexico.
Classification. About 18 species. Subfamily Opuntioideae. Tribe Cylindropuntieae.
Images. • C. alcahes var. burrageana, Austrocylindropuntia cylindrica, Grusonia emoryi (all as Opuntia), Opuntia macrorhiza: Britton & Rose (1919). • Miquelopuntia miquelii, Cumulopuntia ignescens, Grusonia invicta (all as Opuntia): Britton & Rose (1919. • Grusonia bradtiana, with Opuntia tomentosa and Brasiliopuntia brasiliensis (all as Opuntia): Britton & 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’.
