| | The genera of Cactaceae |
Tree cactus. ~ Cephalocereus
Including Pilocereus K. Schum., Pseudopilocereus Buxb.
The plants cerioid; not ‘low and very compacted’. The stems spiny; elongate cylindric; cephaliate, or pseudocephaliate, or neither cephaliate nor pseudocephaliate. The plants branched (usually), or offsetting; erect; shrubby, or tree-like; with well formed trunks (sometimes), or not developing conspicuous trunks; to 1–10 m high. The stems columnar. The branches resembling the main stem; greyish greenish to waxy blue, angled. The stems not segmented; ribbed and grooved. The ribs 3–30; longitudinal. The grooves wide. The plants not conspicuously tuberculate, or conspicuously tuberculate to not conspicuously tuberculate (i.e., the ribs often with cross furrows). The tubercles if so interpreted, connected by the ribs; borne in longitudinal series. The areoles scarcely associated with tubercles, or not tubercle-associated; closely approximating, or distant, or confluent (sometimes confluent in pseudocephalia). The confluent areoles when present, terminating the stems, or lateral. The areoles simple. The flowering areoles differing in form from the non-flowering ones (often forming long woolly hairs, to form cephalia or pseudocephalia), or resembling the non-flowering ones. The areoles often felted; with spines (at least in vegetative parts). The spines clustered; (3–)9–35; 0.1–7 cm long; with radials and centrals differentiated, or showing little or no difference between radials and centrals. Central spines when distinguishable, 0–1, or 1–15. Radial spines (3–)7–24. The spines variable, often translucent, straight, or curved (rarely). The mature stems leafless.
Flowering at night (mostly?). Pollination cheiropterophilous. The flowers lateral (towards the stem tips); one per areole; tubular, or campanulate; sessile; medium-sized to large; 2.5–9 cm long; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium; naked (fleshy, without bracts and areoles, often brown- or purple-tinged). The hypanthial tube cf. the pericarpel; naked; without scales; spineless. The perianth pale pink, or white. The perianth segments relatively short, broad. Stamens numerous.
The mature fruit 2–6 cm long; depressed- globose; with persistent floral remains; without the persistent style characteristic of Cereus (q.v.); smooth, blackening, fleshy to non-fleshy when mature (?); variously dehiscent, or indehiscent; if dehiscent, dehiscing vertically by one slit, or dehiscing vertically by more than one slit, or dehiscing via basal pores, or dehiscing transversely near the top, or irregularly dehiscent (?). The seeds 1.2–2.5 mm long; dark brown, or black; cochleate; not encased in bony arils; with hilum and micropyle conjunct. Cotyledons reduced or vestigial.
Natural Distribution. Mexico, Caribbean, much of tropical South America.
Classification. About 40 species. Subfamily Cactoideae. Tribe Cereeae.
Images. • Pilosocereus alensis: © Zoya Akulova (2018). • Pilosocereus alensis: © Zoya Akulova (2018). • P. gounellei, P. pentaedrophorus, P. polygonus, P. royenii (all as Cephalocereus): Britton & Rose (1920). • P. arrabidae and P. royenii (as barbadensis and nobilis; all as Cephalocereus): Britton & Rose (1920). • P. catingicola and P. rogenii (as brooksianus, all as Cephalocereus), with Brasilicereus phaeacanthus and Leptocereus assurgens: 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’.
