| | The genera of Cactaceae |
~ Lemaireocereus, cf. Hunt (1967)
Including Hertrichocereus Backeb., Isolatocereus Backeb., Isolatocereus (Backeb.) Backeb., Machaerocereus Britton & Rose, Marshallocereus Backeb., Neolemaireocereus Backeb., Rathbunia Britton & Rose, Ritterocereus Backeb.
The plants cerioid; not ‘low and very compacted’. The stems spiny; elongate cylindric; neither cephaliate nor pseudocephaliate. The plants terrestrial and self supporting, or scrambling; branched; prostrate, or erect (or arching); low shrubby (sometimes creeping or forming thickets), or tree-like; with well formed trunks, or not developing conspicuous trunks; to 1–15 m high. The stems columnar, or not columnar. The branches differing in form from the main stem (sometimes candelabra-like, with a well defined trunk), or resembling the main stem; green, stout, cylindrical. The stems not segmented; ribbed and grooved. The ribs (4–)5–12(–19); longitudinal. The grooves wide. The plants conspicuously tuberculate, or not conspicuously tuberculate. The tubercles when present, connected by the ribs; borne in longitudinal series. The areoles associated with tubercles, or not tubercle-associated; usually fairly distant; borne in longitudinal series; simple; woolly; with spines. The spines usually heavy, clustered; 3–26; 0.2–5(–6) cm long; with radials and centrals differentiated (usually), or showing little or no difference between radials and centrals. Central spines when determinable, 0–12. Radial spines 2–18. The spines straight, or curved. The mature stems leafless.
Flowering at night (mostly), or during the day. The flowers lateral; one per areole; slender funnelform, or tubular, or campanulate; sessile; medium-sized to large; 4–14 cm long; regular to somewhat irregular, or very irregular (Rathbunia). The receptacle conspicuously produced beyond the ovary into a tubular hypanthium; usually with spines. The pericarpel with numerous areoles, usually spiny. The hypanthial tube ornamented like the pericarpel; not S-shaped; not naked (with numerous areoles); with scales. The axils of the scales of the hypanthial tube not naked. The hypanthial tube usually with spines. The perianth exposed during bud development; somewhat pink, or white. The perianth segments short, spreading; relatively short, broad; blunt, or pointed.
The mature fruit 2.5–6 cm long; globose, or ovoid; naked, or not naked; spiny, or without spines (the spines usually deciduous); with persistent floral remains to without persistent floral remains (these usually deciduous); fleshy; dehiscent, or indehiscent (?). The seeds large; black; not encased in bony arils. The testa shiny; usually smooth, without ornamentation. Cotyledons reduced or vestigial.
Natural Distribution. Arid southwestern United States, Mexico, Central America, Venezuela, Colombia, Caribbean.
Classification. About 23 species. Subfamily Cactoideae. Tribe Pachycereeae.
Images. • Stenocereus thurberi: © Zoya Akulova (2017). • Stenocereus thurberi: © Zoya Akulova (2017). • Stenocereus thurberi: © Zoya Akulova (2017). • S. griseus (as Lemaireocereus, with Selenicereus setaceus (as Mediocactus) and Leptocereus arboreus: Britton & Rose (1920). • S. dumortieri (= Isolaterocereus, as Lemaireocereus), Peniocereus serpentinus (as Nyctocereus), and Eulychnia iquiquensis: Britton & Rose (1920). • Eulychnia iquiquensis, with Stenocereus dumortieri (as Lemaireocereus) and Peniocereus serpentinus (as Nyctocereus): 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’.
