mistletoe cactus

Cactus and tree dweller 

Rhipsalis is a genus of about 35 species in Central and South America. Only one species (Rhipsalis baccifera) is also native to Africa and Asia. Rhipsalis is called the mistletoe cactus because it grows in trees and also produces white, sticky, mistletoe-like berries.

Rhipsalis grows in tropical forests, which does not correspond to the image of a cactus as a desert plant. Yet it is not so strange: cacti of this genus are epiphytic, they grow on trees, so they get much sunlight and often receive little water - ideal conditions for a cactus.

The mistletoe cactus has a limited range in Brazil. Today the clumpy mistletoe cactus is only found in public parks in and around Rio de Janeiro. Although the plant has colonized urban areas, it is no longer found in the wild and is thus critically endangered.

A cactus in a rainforest

The majority of cactus species grow in the semi-desert but some can be found in rainforests. One such cactus is the epiphytic Rhipsalis mesembryanthemoides that grows on trees particular in the humus rich hollows in the stem or branches.

The plant forms long, round stems that can grow to 50 cm in length and 2 cm thick. These stems are covered in small branchlets with areoles from where the flowers appear. The fruit are small, white berries that are eaten by birds. These fruit bearing plants bear some resemblance to the native mistletoe, hence the suggested vernacular name – bushy mistletoe cactus.

Rhipsalis mesembryanthemoides belongs to the genus Rhipsalis with all members characterised by stems covered in branchlets. This species is cultivated in abundance to be sold as houseplants and can be found for sale in the Netherlands. In the Utrecht Botanic Garden there is a large collection of epiphytic cacti.

Ecology and habitat

Rhipsalis mesembryanthemoides occurs in a small region in the Brazilian city of Rio de Janeiro on both sides of the Baja de Guanabara, from sea level up to 600 m. They are epiphytic on trees and are now only found in city parks. The original habitat was probably lowland forest.

Threat

Its native environment has completely disappeared because of the encroaching urbanisation. Despite its occurrence in urban area this species up until now has failed to establish itself within more natural habitats in the area and numbers are declining due to the warmer, drier microclimate of the city. There are now only a couple of thousand individuals left. The city parks are not officially protected areas and the survival of this species is uncertain as it depends on park management.