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| The genera of Cactaceae |
Night-blooming cactus.
Including Wilmattea Britton & Rose
The plants cerioid; not ‘low and very compacted’. The stems spiny. The plants often huge, epiphytic, or scrambling, or climbing, or lithophytic, or terrestrial and self supporting (rarely); often producing aerial roots; branched; prostrate, or erect, or pendent. The branches differing in form from the main stem, or resembling the main stem. The main stem sometimes more or less cylindrical. The branches winged or angled; to to 1000 cm long (10 metres). The stems segmented, or not segmented; ribbed and grooved. The ribs 3(–5); longitudinal. The grooves very wide. The plants conspicuously tuberculate to not conspicuously tuberculate (depending on interpretation of notched branch ribs or angles). The tubercles if present, connected by the ribs; borne in longitudinal series. The areoles associated with tubercles to not tubercle-associated; distant; borne in longitudinal series; simple (in notches along the ribs or angles, distant). The flowering areoles differing in form from the non-flowering ones (being naked), or resembling the non-flowering ones. The areoles shortly woolly; without glochids; with spines (these few, short and small or inconspicuous), or without spines (rarely). The spines solitary, or paired, or clustered; 1–6(–8); 0.1–0.4(–1) cm long; showing little or no difference between radials and centrals. The mature stems leafless.
Flowering at night. The flowers solitary; lateral; one per areole; funnelform; sessile; large to very large; (3–)20–32 cm long; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium. The pericarpel stout, with broad, triangular, leaflike scales. The hypanthial tube clearly produced beyond the ovary; not naked; with scales (these broad, foliaceous). The axils of the scales of the hypanthial tube more or less naked. The hypanthial tube spineless. The perianth with distinct calyx and corolla, or sequentially intergrading from sepals to petals, or of ‘tepals’; white (mostly), or red (variously with greenish, red or purplish sepals and usually white petals). The perianth segments elongate, relatively narrow; acuminate. Stamens very numerous; adnate to the perianth (inserted in the tube and throat, the lowermost not basally united); not exserted; not grouped (in a continuous series).
The mature fruit (2.5–)4–10 cm long; globose, or ovoid; usually red; not naked (covered with broad scales having naked axils); without spines; with persistent floral remains, or without persistent floral remains; edible, fleshy; dehiscent to indehiscent; if dehiscent, irregularly dehiscent. The seeds numerous, small, black; ovoid, or reniform; not encased in bony arils; with hilum and micropyle fused; with a mucilage sheath. The testa shiny; minutely spotted, or smooth, without ornamentation. Cotyledons reduced or vestigial.
Natural Distribution. Southern Mexico, Caribbean, Centra America, northern South America.
Classification. 19 species. Subfamily Cactoideae. Tribe Hylocereeae.
Cf. Hunt (1967).
Images. • Hylocereus undatus: © Zoya Akulova (2012). • Hylocereus acamponis: Britton & Rose (1920). • Hylocereus monacanthus: Britton & Rose (1920). • Hylocereus undatus: Britton & Rose (1920). • Hylocereus lemairei: Britton & Rose (1920). • Hylocereus trigonus and Selenicereus boeckmannii: Britton & Rose (1920). • Hylocereus undatus, H. minutiflorus (as Wilmattea), Selenicereus grandiflorus: Britton & Rose (1920). • Arrojadoa rhodantha, with Cleistocactus baumannii and Hylocereus stenopterus: 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’.
