Rhipsalis

"Mistletoe cactus" redirects here. This may also mean specifically Rhipsalis baccifera, or, more generally, other Rhipsalideae.
"Cactus mistletoe" is Tristerix aphylla, a Patagonian Argentinean and Chilean species of mistletoe, whose preferred hosts are two species of cactus.

Rhipsalis
Flowering Rhipsalis cereuscula
Scientific classification
Kingdom:Plantae
Clade:Angiosperms
Clade:Eudicots
Order:Caryophyllales
Family:Cactaceae
Subfamily:Cactoideae
Tribe:Rhipsalideae
Genus:Rhipsalis
Gaertn.
Species

Numerous, see text

Synonyms

Rhipsalis is a genus of 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. Additionally they 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 (those which live on other plants without damaging them).

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. Hence Cassytha is often indicated as a generic synonym for Rhipsalis.

Ecology and distribution

Rhipsalis is found as an 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, but additionally in tropical Africa, Madagascar and Sri Lanka. It is the only cactus with a natural occurrence outside the New World.

Rhipsalis pilocarpa 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 (e.g. Rhipsalis neves-armondii), whereas other have very thin, filiform stems (e.g. Rhipsalis baccifera, Rhipsalis clavata). In the majority of species, spines are missing or occur only in the juvenile stage (this is most prominent in Rhipsalis dissimilis). 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.

Species

Based on the latest taxonomic treatment in the New Cactus Lexicon (Hunt et al. 2006), 35 species of Rhipsalis are recognised.

References

    Literature

    • E. F. Anderson (2001): The Cactus Family. Timber Press.
    • W. Barthlott & N.P. Taylor (1995): Notes towards a Monograph of Rhipsalideae (Cactaceae). Bradleya 13, pp. 43–79.
    • W. Barthlott (1983): Biogeography and evolution in neo- and palaeotropical Rhipsalinae (Cactaceae). In: Kubitzki, K. (Ed.) Proc. Int. Symp. Dispersal and Distribution, Sonderbd. naturwiss. Ver. Hamburg 7: 241-248.
    • J. Hugo Cota-Sánche [Vivipary in the Cactaceae: Its taxonomic occurrence and biological significance], Flora - Morphology, Distribution, Functional Ecology of Plants ; Volume 199, Issue 6, 2004, Pages 481-490 doi:10.1078/0367-2530-00175
    • D. Hunt, N. Taylor, G. Charles (2006): The New Cactus Lexicon. dh books.
    • N. P. Taylor, D. Zappi (2004): Cacti of Eastern Brazil. Kew Publishing.
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