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| The genera of Cactaceae |
Including Monvillea Britton & Rose (p.p.)
The plants cerioid; not ‘low and very compacted’. The stems spiny; elongate cylindric; pseudocephaliate. The plants terrestrial and self supporting, or scrambling; little to much branched; initially weakly erect, or prostrate (subsequently); shrubby to tree-like; to 6 m high (when erect). The stems not columnar, or columnar to not columnar. The branches cylindrical; to 500 cm long; 1.5–3 cm in diameter. The stems not segmented; ribbed and grooved. The ribs 4–14; longitudinal. The grooves wide, or deep and narrow. The plants not conspicuously tuberculate. The areoles not tubercle-associated; distant; borne in longitudinal series; simple (round, grey). The flowering areoles resembling the non-flowering ones. The areoles with spines. The spines clustered; 7–20; 0.2–1.5 cm long; with radials and centrals differentiated, or showing little or no difference between radials and centrals. Central spines when determinable, 1–3. Radial spines 6–9. The spines stiff; straight; terete (acicular or awl-shaped). The mature stems leafless.
Flowering at night. The flowers lateral; one per areole; sturdy funnelform to campanulate; sessile; large; 8–12 cm long; regular, or somewhat irregular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium; not naked; with scales; spineless. The pericarpel stout, thich walled, fleshy, often curved, with minute scales but no hairs, bristles or spines. The hypanthial tube like the pericarpel; not naked; with scales (these tiny). The axils of the scales of the hypanthial tube more or less naked. The hypanthial tube spineless. The perianth yellowish green to white; limb relatively large.
The mature fruit 3 cm long; shortly ovoid; red; with persistent floral remains; shortly ovoid, with persistent floral remains, fleshy; dehiscent; dehiscing vertically by one slit ("laterally along one side"). The seeds elongate ovoid, somewhat laterally compressed, tuberculate, black; not encased in bony arils; with hilum and micropyle conjunct. Cotyledons reduced or vestigial.
Natural Distribution. Bolivia, Ecuador, Peru, Venezuela and trinidad.
Classification. 2 species. Subfamily Cactoideae. Tribe Cereeae.
Images. • Praecereus euchlorus susp. diffusa (as Monvillea), flower: Britton & Rose (1920). • Praecereus euchlorus subsp. smithianus: Britton & Rose (1920).
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’.
