| | The genera of Cactaceae |
Triangle cactus, Sword cactus.
Including Dendrocereus Britton & Rose, Monvillea Britton & Rose (p.p.)
The plants cerioid; not ‘low and very compacted’. The stems spiny; elongate cylindric. The plants clambering, trailing or scrambling, or terrestrial and self supporting; not producing aerial roots; many branched; prostrate, or erect (often, at least at first), or pendent; shrubby, or tree-like; with well formed trunks (Dendrocereus), or not developing conspicuous trunks. The main stem remaining dominant, or not remaining dominant. The branches angled (or ribbed, 3–4 sided), or cylindrical. The stems segmented, or not segmented; ribbed and grooved (or angled). The ribs 3–5(–7); more or less longitudinal (sometimes wavy); thin or rarely flattened. The grooves wide. The plants conspicuously tuberculate to not conspicuously tuberculate (i.e., with conspicuously notched ribs). The tubercles connected by the ribs; borne in longitudinal series (sometimes wavy). The areoles associated with tubercles (i.e., in the notches); distant (2–6 cm apart); borne in longitudinal series (along the ribs); simple; without glochids; with spines (usually), or without spines (sometimes, A. subinermis). The spines when present, clustered; (2–)6–10(–15); 0.5–7 cm long; with radials and centrals differentiated (with 1–2(-4) centrals longer), or showing little or no difference between radials and centrals. Central spines 1–2, or 4. Radial spines 1–8. The mature stems leafless.
Flowering at night. The flowers solitary; lateral; one per areole; funnelform; sessile; large; 12–25 cm long; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium; not naked; with scales; with spines. The pericarpel subtending conspicuous areoles with short spines. The hypanthial tube stout, elongate, rather rigid, bearing small scales; not naked; with scales. The axils of the scales of the hypanthial tube not naked. The hypanthial tube with spines. The perianth members numerous; green and white; limb relatively large. The perianth segments spreading (widely); elongate, relatively narrow; pointed. Stamens numerous; adnate to the perianth (inserted in the tube and throat); not exserted.
The mature fruit globose, or ellipsoidal, or pyriform; green, or red; naked, or not naked; spiny, or without spines; fleshy (with red pulp); dehiscent, or indehiscent. The seeds not encased in bony arils. Cotyledons reduced or vestigial.
Natural Distribution. Tropical America and Cuba, with A. pentagonus constituting an introduced weed elsewhere.
Classification. About 6 species. Subfamily Cactoideae. Tribe Pachycereeae.
Cf. Hunt, 1967.
Images. • A. nudiflorus (as Dendrocereus) and Peniocereus hirschtianus (as Nyctocereus guatemalensis): Britton & Rose (1920). • Acanthocereus tetragonus (as pentagonus) and A. subinermis: 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’.
