Rhipsalis
Rhipsalis is a genus of epiphytic flowering plants in the cactus family, typically known as mistletoe cacti. They are found in parts of Central America, the Caribbean and northern regions of South America. They also inhabit isolated locations in Africa and Asia, and are the only cactus group naturally occurring in the Old World. This is the largest and most widely distributed genus of epiphytic cacti.
The scientific name Rhipsalis derives from the Ancient Greek term for wickerwork, referring to the plants' morphology.
History
The genus was described by Joseph Gaertner in 1788. But when he described the plant, he had in fact not realised it was a cactus. Instead, he assumed he had found a new species of Cassytha, a parasitic laurel from a completely different plant family.Ecology and distribution
Rhipsalis is found as pendulous epiphyte in tropical rainforests, some species may also grow epilithic or, rarely, terrestrial. The genus is found widely in Central America, parts of the Caribbean and a great part of northern and central South America. The center of diversity of Rhipsalis lies in the rainforests of the Mata Atlantica in southeastern Brazil. It is found throughout the New World, and additionally in tropical Africa, Madagascar and Sri Lanka. It is the only cactus with a natural occurrence outside the New World.'' fruit
Morphology
The morphology of Rhipsalis is very variable. The plants can grow mostly pendent, few grow more or less upright or sprawling. There are three main stem shapes: terete, angular and flattened. The stems are succulent, but the degree of succulence varies between the species. Some have very thick stems, whereas other have very thin, filiform stems. In the majority of species, spines are missing or occur only in the juvenile stage. Rhipsalis pilocarpa has stems and fruits densely covered by bristes, making this species easily distinguishable from all other Rhipsalis.The flowers are borne lateral or apical and are actinomorphic with a varying number of perianth segments, stamens and carpels. They are small, usually about 1 cm in diameter, white or whitish in most species. Yellowish flowers occur in R. dissimilis and R. elliptica and R. hoelleri is the only Rhipsalis species with red flowers. The fruits are always berries, they are whitish or coloured pink, red or yellow. Vivipary has been observed in R. micrantha and R. baccifera.
Species
Based on taxonomic treatment in The New Cactus Lexicon, 35 species divided into five subgenera are recognised.| Subgenus | Image | Scientific name | Distribution |
| Calamorhipsalis | Rhipsalis dissimilis K.Schum. | Brazil | |
| Calamorhipsalis | Rhipsalis floccosa Salm-Dyck ex Pfeiff. | Argentina, Bolivia, Brazil, Paraguay, Peru, Venezuela | |
| Calamorhipsalis | Rhipsalis hoelleri Barthlott & N.P.Taylor | Brazil | |
| Calamorhipsalis | Rhipsalis neves-armondii K.Schum. | Brazil | |
| Calamorhipsalis | Rhipsalis pacheco-leonis Loefgr. | Brazil | |
| Calamorhipsalis | Rhipsalis paradoxa Salm-Dyck | Brazil | |
| Calamorhipsalis | Rhipsalis puniceodiscus G.Lindb. | Brazil | |
| Calamorhipsalis | Rhipsalis trigona Pfeiff. | Brazil | |
| Erythrorhipsalis | Rhipsalis aurea M.F.Freitas & J.M.A.Braga | Brazil | |
| Erythrorhipsalis | Rhipsalis burchellii Britton & Rose | Brazil | |
| Erythrorhipsalis | Rhipsalis campos-portoana Loefgr. | Brazil | |
| Erythrorhipsalis | Rhipsalis clavata F.A.C.Weber | Brazil | |
| Erythrorhipsalis | Rhipsalis cereuscula Haw. | Argentina, Bolivia, Brazil, Paraguay, Uruguay | |
| Erythrorhipsalis | Rhipsalis juengeri Barthlott & N.P.Taylor | Brazil | |
| Erythrorhipsalis | Rhipsalis ormindoi N.P.Taylor & Zappi | Brazil | |
| Erythrorhipsalis | Rhipsalis pilocarpa Loefgr. | Brazil | |
| Erythrorhipsalis | Rhipsalis pulchra Loefgr. | Brazil | |
| Erythrorhipsalis | Rhipsalis agudoensis N.P. Taylor | Brazil | |
| Erythrorhipsalis | Rhipsalis baccifera Stearn | Madagascar, Seychelles, Mauritius, Reunion, Sri Lanka | |
| Erythrorhipsalis | Rhipsalis cereoides Backeb. & Voll | Brazil | |
| Erythrorhipsalis | Rhipsalis crispata Pfeiff. | Brazil | |
| Erythrorhipsalis | Rhipsalis crispimarginata Loefgr. | Brazil | |
| Erythrorhipsalis | Rhipsalis cuneata Britton & Rose | Bolivia | |
| Erythrorhipsalis | Rhipsalis elliptica G.Lindb. ex K.Schum. | Brazil | |
| Erythrorhipsalis | Rhipsalis ewaldiana Barthlott & N.P. Taylor | Brazil | |
| Erythrorhipsalis | Rhipsalis goebeliana Backeb. | Bolivia | |
| Erythrorhipsalis | Rhipsalis grandiflora Haw. | Brazil | |
| Erythrorhipsalis | Rhipsalis hileiabaiana Koro & Barthlott | ||
| Erythrorhipsalis | Rhipsalis lindbergiana K.Schum. | Brazil | |
| Erythrorhipsalis | Rhipsalis mesembryanthemoides Haw. | Brazil | |
| Erythrorhipsalis | Rhipsalis micrantha Kunth | Costa Rica, Ecuador, Peru, Venezuela | |
| Erythrorhipsalis | Rhipsalis oblonga Loefgr. | Brazil | |
| Erythrorhipsalis | Rhipsalis olivifera N.P.Taylor & Zappi | Brazil | |
| Erythrorhipsalis | Rhipsalis occidentalis Barthlott & Rauh | Ecuador, Peru, Suriname | |
| Erythrorhipsalis | Rhipsalis pachyptera Pfeiff. | Brazil | |
| Erythrorhipsalis | Rhipsalis pentaptera Pfeiff. | Brazil | |
| Erythrorhipsalis | Rhipsalis russellii Britton & Rose | Brazil | |
| Erythrorhipsalis | Rhipsalis sulcata F.A.C. Weber | Brazil | |
| Erythrorhipsalis | Rhipsalis teres Steud. | Brazil | |
| Erythrorhipsalis | Rhipsalis triangularis Werderm. | Brazil |
Recent molecular studies showed paraphyly of three subgenera as previously circumscribed. So a new subgeneric classification of Rhipsalis with only monophyletic subgenera Rhipsalis, Calamorhipsalis and Erythrorhipsalis is proposed.