| | The genera of Cactaceae |
Including Encephalocarpus A. Berger
The plants condensed-cactoid; low and very compacted in their entirety; vegetatively reduced almost entirely to rosettes of large, trigonous tubercles, or not vegetatively reduced to tubercles. The stems spiny; discoid to globose (or depressed-globose); 2–6 cm in diameter; apically depressed, or not apically depressed. The plants geophytic; branched, or unbranched (single- or multiple stemmed, with spindle-shaped roots); erect; to 0.02–0.06 m high. The stems not segmented; not ribbed and grooved. The plants conspicuously tuberculate. The tubercles triangular or elliptical in outline; longitudinally grooved adaxially from the areole towards their ‘axils’ to adaxially ridged from the areole towards the ‘axil’ (the ventral surface of the young tubercles with a rudimentary groove represented by a band of hairs, or a shallow corky ridge, linking the spiniferous areole with the floriferous meristem). The tubercles not connected by ribs; spirally disposed. The areoles associated with tubercles; distant; spirally disposed; with the abaxial spine cluster at the tubercle tip connected to the adaxial floriferous meristem nearer its axil by a recessed linear isthmus or a ridge to distinctly bipartite, with the abaxial spine cluster at the tubercle tip and no recessed isthmus or other visible connection with the adaxial, floriferous meristem near its base (i.e., with only rudimentary areolar grooves or ridges); with spines (on the outer component). The spines clustered; 7–69; 0.07–0.5 cm long; showing little or no difference between radials and centrals (more or less pectinate); whitish. The mature stems leafless.
Flowering during the day. The flowers terminal (borne at the bases of the nascent tubercles); one per areole; funnelform, or campanulate; sessile; small to medium-sized; 1.5–3 cm long (1.3–3.0 cm in diameter); regular. The receptacle conspicuously produced beyond the ovary into a tubular hypanthium; naked. The hypanthial tube naked; without scales; spineless. The perianth red to purple (magenta). The perianth segments relatively short, broad; pointed. Stamens adnate to the perianth (inserted in the tube or throat).
The mature fruit 0.38–0.8 cm long; globose; greenish brown, or green; not naked; without spines; without persistent floral remains; non-fleshy when mature; indehiscent. The seeds 1–1.3 mm long; reddish brown; reniform; not encased in bony arils. The testa only somewhat reticulately or striately patterned. Cotyledons reduced or vestigial.
Natural Distribution. Mexico.
Classification. 2 species. Subfamily Cactoideae. Tribe Cacteae.
Cf. Hunt (1967).
Images. • Pelecyphora aselliformis: © Zoya Akulova (2018). • Pelecyphora aselliformis: Bot. Mag. 99 (1873).
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’.
