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| The genera of Cactaceae |
Orchid cacti, ‘Epyphyllums’.
Including Aporocactus Lem., Aporocereus Fric & Kreuz. (orth. var.), Bonifazia Standl. & Steyerm., Chiapasia Britton & Rose, Disisocactus Kunze (orth. var.), Disocereus Fric & Kreuz. (orth. var.), Heliocereus (A. Berger) Britton & Rose, Lobeira Alexander, Mediocereus Fric & Kreuz. (orth. var.), Nopalxochia Britton & Rose, Pseudonopalxochia Backeb., Trochilocactus Linding., Wittia K.Schum., Wittiocactus Rauschert
The plants non-laticiferous; cerioid; not ‘low and very compacted’. The stems spiny (or bristly), or not spiny; neither cephaliate nor pseudocephaliate. The plants terrestrial and self supporting, or epiphytic, or lithophytic; judging from published photos, not producing aerial roots (?); branched; with cladodes, or without cladodes. The cladodes with midribs, or without midribs. The plants prostrate, or erect, or pendent; more or less shrubby; solitary; to nearly 1 m long. The branches differing in form from the main stem (often), or resembling the main stem. The main stem flattened, or more or less cylindrical. The branches flattened, or cylindrical, or flattened and cylindrical (often becoming flattened above their cylindrical bases, often with a pronounce median nerve); to 15–100 cm long. The stems segmented, or not segmented; not annually articulating; ribbed and grooved, or not ribbed and grooved. The ribs when present, longitudinal. The grooves if present, wide. The plants conspicuously tuberculate, or not conspicuously tuberculate (depending on interpretation of notched, serrate or crenate ribs or branch margins). The tubercles borne in longitudinal series, or borne along the margins of the flattened branches. The areoles associated with tubercles to not tubercle-associated; borne in longitudinal series, or borne along the margins of the flattened branches; simple. The flowering areoles resembling the non-flowering ones. The areoles with bristles, or without bristles; with spines (bristly), or without spines (commonly). The spines when present, 1–30; 0.1–1.5 cm long; with radials and centrals differentiated, or showing little or no difference between radials and centrals (usually). Central spines in D. martianus, 3–4. Radial spines in D. martianus, 6–10. The mature stems leafless.
Flowering at night, or during the day (Aporocactus, Heliocereus). The flowers lateral; one per areole (usually), or more than one per areole; variously narrowly campanulate, or tubular to funnelform; sessile; medium-sized to very large; 3–17 cm long; fragrant; regular to somewhat irregular, or very irregular (Aporocactus). The receptacle conspicuously produced beyond the ovary into a tubular hypanthium to scarcely produced beyond the ovary. The hypanthial tube slender, not naked; with scales (these few, small). The axils of the scales of the hypanthial tube more or less naked (?). The hypanthial tube spineless. The perianth sequentially intergrading from sepals to petals, or of ‘tepals’; segments rather few; brightly coloured, white, or cream, or yellow, or orange, or red, or pink; limb relatively large, or short or none. The perianth segments spreading, or recurved; mostly elongate, relatively narrow, or relatively short, broad (D. nelsonii); pointed, or acuminate, or apiculate (D. nelsonii). Stamens few to many; and style exserted beyond the perianth. Gynoecium inferior.
The mature fruit 1–14 cm long; globose, or ovoid; of assorted colours; naked, or not naked (then with small scales); without spines; berry-like fleshy, or non-fleshy when mature (?); indehiscent (?). The seeds black; slightly reniform, or ovoid; not encased in bony arils; with hilum and micropyle fused; with a mucilage sheath. The testa minutely rugose, or spotted. Embryo strongly curved. Cotyledons reduced or vestigial.
Natural Distribution. Central America (mainly), also northern South America and West Indies.
Classification. 16 species. Subfamily Cactoideae. Tribe Hylocereeae.
Cf. Hunt, 1967.
Images. • Disocactus flagelliformis(as Aporocactus spp.: Britton & Rose (1920). • Disocactus schrankii (as Heliocereus elegantissimus), D. speciosus (as Heliocereus) and ‘Heliocereus portoricensis’ (= ?): Britton & Rose (1920). • D. flagelliformis (L.) Barthlott (as Aporocactus), Bot. Mag. 17 (1786). • cf. Disocactus speciosus (Cav.) Barthlott (as Cereus speciosissimus), Bot. Reg. 49, 1842. • Disocactus biformis, as Phyllocactus: Bot. Mag. 101 (1875).
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’.
