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| The genera of Cactaceae |
Christmas cactus, Easter cactus.
Including Epiphyllanthus A. Berger, Epiphyllum Pfeiff., Opuntiopsis Knebel (nom. inval.), Cryptocactus K. Schum., Zygocereus Fric & Kreuz. (orth. var.), Zygocactus K. Schum.
The plants cerioid; not ‘low and very compacted’. The stems spiny, or not spiny. The plants epiphytic, or scrambling, or lithophytic; producing aerial roots; much branched (often dichotomously, but irregularly in Epiphyllum); with cladodes (usually, at least on distal parts of the branches), or without cladodes (S. microsphaerica). The cladodes with midribs to without midribs. The plants prostrate, or erect, or pendent. The branches flattened, or flattened and cylindrical (sometimes becoming cylindrical and woody with age); in S. microsphaerica, 2–5 cm in diameter; where flat, 0.2–4.5 cm wide. The stems segmented (usually into cladodes, these 1.5–7 cm long); seemingly annually articulating; not ribbed and grooved. The plants conspicuously tuberculate to not conspicuously tuberculate (the tubercles when present represented by serration or crenation of the margins). The tubercles if thus interpreted, spirally disposed, or borne in longitudinal series, or borne along the margins of the flattened branches, or scattered. The areoles only dubiously associated with tubercles, or not tubercle-associated; distant and confluent (with composite terminal flowering areoles). The confluent areoles at the ends of terminal, flattened stem segments. The areoles spirally disposed, or borne along the margins of the flattened branches, or borne along the margins of the flattened branches and scattered on the surfaces (the sterile ones in Epiphyllanthus scattered over the surfaces of the joints, Opuntia-like, in others confined to the crenate or serrate margins, and the flowering ones always composite and terminal on older segments); simple. The flowering areoles differing in form from the non-flowering ones (being terminal and composite). The areoles not woolly; with bristles, or without bristles; with spines, or without spines (short and bristle-like, or stiffening with age). The spines when present, solitary to clustered; (0–)1–80. The mature stems leafless.
Flowering at night and during the day. Pollination in at least some species ornithophilous. The flowers terminal; one per areole; sessile; medium-sized to large; 5–9 cm long; regular to very irregular (radially to strongly bilaterally symmetrical). The receptacle conspicuously produced beyond the ovary into a tubular hypanthium. The pericarpel mostly naked, with ornamentation grading into the tube. The hypanthial tube with petaloid scales, the mouth straight or oblique, produced from the receptacle which is terete or ribbed around the ovary and mostly naked below; not naked; with scales (these petaloid); spineless. The perianth sequentially intergrading from sepals to petals, or petaline, or of ‘tepals’; varying widely in colour, white, or yellow, or orange, or red to pink, or purple. Stamens numerous; adnate to the perianth; not separated from the perianth by a ring of hairs; (and style) exserted beyond the perianth; in groups; coherent and free of one another (with a distinct inner series united basally to form a short tube around the style enclosing the nectar chamber).
The mature fruit ribbed to winged in cross section, globose, or pyriform; white, or green, or yellow, or red; with persistent floral remains, or without persistent floral remains; berries, fleshy; green, yellow, white or red indehiscent. The seeds 1 mm long; brown to black; ovoid ("oval"), or reniform; not encased in bony arils; with hilum and micropyle fused; with a mucilage sheath. The testa shiny; minutely pitted, or smooth, without ornamentation. Cotyledons reduced or vestigial.
Natural Distribution. Southeastern Brazil.
Classification. 4–5 species (and hybrids). Subfamily Cactoideae. Tribe Rhipsalideae.
Cf. Hunt (1967).
Images. • Schlumbergera russelliana: © www.iperity.com. • Schlumbergera russelliana: © www.iperity.com.
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’.
