| | The genera of Cactaceae |
~ Cereus, Borzicactus p.p., cf. Hunt (1967)
Including Arequipa Britton & Rose, Arequipiopsis Kreuz. & Buining, Morawetzia Backeb., Submatucana Backeb.
The plants succulent; cerioid, or cerioid to condensed-cactoid (more or less spherical when young but becoming more or less columnar in Arequipa and Submatucana); low and very compacted in their entirety, or not ‘low and very compacted’. The stems spiny (usually with hairy stems); globose, or shortly cylindric; cephaliate (e.g., Morawetzia), or pseudocephaliate. The plants sparsely basally branched; erect, or prostrate (rarely); neither shrubby nor tree-like, or shrubby to tree-like; with well formed trunks (rarely), or not developing conspicuous trunks; solitary, or clustering (often clump-forming); to 0.6–3 m high. The stems columnar, or not columnar. The main stem remaining dominant, or not remaining dominant; more or less cylindrical. The branches cylindrical; 5–12 cm in diameter. The stems not segmented; ribbed and grooved. The ribs 10–25; longitudinal; low. The plants conspicuously tuberculate, or not conspicuously tuberculate (then notched). The tubercles connected by the ribs; borne in longitudinal series. The areoles associated with tubercles to not tubercle-associated (the associated with notches); closely approximating to distant. The components of adjacent areoles not obscuring details of the plant body. The areoles borne in longitudinal series; simple. The flowering areoles differing in form from the non-flowering ones (in cephalia), or resembling the non-flowering ones. The areoles with spines. The spines clustered; 8–25; 0.4–10 cm long; with radials and centrals differentiated (the centrals longer). Central spines 1–6(–8); conspicuously forming a cross, or not forming a cross. Radial spines (5–)10–30. The spines straight; terete. The mature stems leafless.
Flowering during the day. The flowers sub- terminal to lateral (towards the stem tips); one per areole; funnelform; sessile; medium-sized to large; 6–10 cm long; somewhat irregular to very irregular (zygomorphic). The receptacle conspicuously produced beyond the ovary into a tubular hypanthium. The pericarpel with numerous hairy areoles. The hypanthial tube long-cylindric, straight to somewhat curved, sometimes laterally compressed; not S-shaped; not naked; with scales. The axils of the scales of the hypanthial tube not naked (densely to scarcely hairy), or more or less naked. The hypanthial tube spineless. The perianth orange, or red, or purple; limb short or none. The androecium including staminodes, or without staminodes (?).
The mature fruit 1.5–6 cm long (poorly recorded); globose to ovoid; hollow, fleshy, or non-fleshy when mature; dehiscent, or indehiscent; dehiscing via basal pores. The seeds black; ovoid ("broadly oval"); not encased in bony arils; without a mucilage sheath. The testa shiny, or dull. Cotyledons reduced or vestigial.
Natural Distribution. Northern Argentina, Bolivia, northern Chile and Peru.
Classification. About 9 species. Subfamily Cactoideae. Tribe Trichocereeae.
Images. • Oreocereus doelzianus: © Zoya Akulova (2016). • Oreocereus doelzianus: © Zoya Akulova (2018). • Oreocereus celsianus: 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’.
