| | The genera of Cactaceae |
Including Binghamia Britton & Rose, Pseudoespostoa Backeb., Thrixanthocereus Backeb.
The plants cerioid; not ‘low and very compacted’. The stems spiny; elongate cylindric; cephaliate (E. nana), or pseudocephaliate (usually, laterally), or cephaliate and pseudocephaliate (the spectacular lateral cephalia generally forming over several reduced and modified ribs). The plants branched (from the base or above); erect; shrubby, or tree-like; with well formed trunks, or not developing conspicuous trunks; solitary, or clustering; to 1.5–9 m high. The stems columnar (mostly), or not columnar. The branches resembling the main stem. The main stem more or less cylindrical. The branches cylindrical. The stems not segmented; ribbed and grooved. The ribs many; longitudinal; low. The grooves wide. The plants not conspicuously tuberculate. The areoles closely approximating to distant; borne in longitudinal series; simple. The flowering areoles differing in form from the non-flowering ones (their long bristly hairs and spines forming the conspicuous beards). The areoles hairy; without glochids; with spines. The spines clustered (numerous, some stout and others hairlike, the spines and hairs sometimes forming a webbing over the stems); 12–45(–90); 0.4–5(–10) cm long; with radials and centrals differentiated, or showing little or no difference between radials and centrals. Central spines when differentiated, (0–)1–4. Radial spines (3–)20–90. The mature stems leafless.
Flowering at night, or at night and during the day. The flowers lateral, or terminal and lateral (originating in the pseudocephalia); one per areole; tubular, or campanulate; sessile; small to large; 2.5–8 cm long; regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium to scarcely produced beyond the ovary (short); not naked; with scales; spineless. The pericarpel spineless, with small acute scales. The hypanthial tube not S-shaped; not naked; with scales. The axils of the scales of the hypanthial tube usually hairy, not naked. The hypanthial tube spineless. The perianth parts short; white, or yellow, or red (-ish); limb relatively large. The perianth segments spreading, or recurved. Stamens numerous; adnate to the perianth (inserted in the throat and tube, the lowermost on a collar that partially encloses the nectar chamber); not grouped.
The mature fruit 1.6–5 cm long; globose to ovoid; green, or red; more or less naked, or not naked (then with hair tufts); without spines; with persistent floral remains; fleshy; indehiscent. The seeds small; brown to black; diverse in shape, oval to almost hat-shaped, the hilum large and broad; not encased in bony arils. The testa dull (dull); verrucose and spotted (more or less verrucose, minutely spotted). Cotyledons reduced or vestigial.
Natural Distribution. South of the equator in Ecuador, Peru and Bolivia.
Classification. 15 species. Subfamily Cactoideae. Tribe Trichocereeae.
Cf. Hunt, 1967.
Images. • Espostoa mirabilis: © Zoya Akulova (2018). • Espostoa nana: © Zoya Akulova (2018). • Espostoa melanostele (as Binghamia), with Harrisia fernowii and H. pomanensis (as bomplandii): Briton & Rose (1920). • Habit: Espostoa melanostele (as Binghamia) and Haageocereus limensis (as Binghamia acrantha): 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’.
