Epiphytic Cactus Species Overview
by Linda Sinkovic
Some people have never heard of epiphytic cacti. People might think there is no such thing -- cacti growing in forest trees? Everyone knows cacti only grow in deserts, right?
Epiphytic cacti do indeed exist. Some are grown as indoor plants -- or even outdoors -- even by those people who doubt cacti would grow in a forest. So let's set the record straight -- Christmas cacti (and other holiday cacti) and hybrid epicacti (commonly known as “epiphyllum”) really are cacti. And though they are hybrids, their wild ancestors still grow in trees in subtropical and tropical forests.
Interested in a very brief overview of these epiphytic cacti species?
First, let's talk about the ancestors of the hybrids known collectively as “Holiday Cactus".
Whether “Christmas Cactus” or “Thanksgiving Cactus” -- there is really no difference -- these are hybridized from species in the genus Schlumbergera, which occur in the forested mountains of southeastern Brazil.
Next, the commonly grown “Easter Cactus” is a hybrid derived from species in the
Rhipsalidopsis genus, which is also found in the forested mountains of southeastern Brazil.The closely-related genus Hatiora is found in the same area.
Although the genera Lepismium and Rhipsalis are related to Schlumbergera and the other
genera mentioned above, their common ancestry is much farther back in time. Also found in South America, species in these genera are sometimes called “Mistletoe Cacti”. The largest concentration of species in both genera is found in southeastern Brazil, but there are a few species of Lepismium occurring in Bolivia and northern Argentina. The Rhipsalis genus has species which are found from Colombia, Ecuador, and Peru through Bolivia and Paraguay to northern Argentina. One Rhipsalis species (Rhipsalis baccifera) is very widely distributed; there are subspecies in southeastern Brazil, in Central America and the Caribbean, as well as much of northwestern South America. In addition, Rhipsalis baccifera is the only naturally occurring cactus outside of the western hemisphere, and subspecies are found in the central part of Africa, Madagascar, and Sri Lanka (and on some islands in the Indian Ocean). This is a big deal because no other species of cacti have been found naturally occurring outside of the western hemisphere.
For a nice presentation on Rhipsalis click here:
All epiphytic cactus species are not closely related, and their similar environments have shaped them into similar forms (known as convergent evolution). Although their forms look similar, the two separate lineages of Pfeiffera and Lymanbensonia are not closely related to Rhipsalis and Lepismium. Both also occur in South America; Pfeiffera is found from Bolivia (the eastern Andes) to northern Argentina. Lymanbensonia occurs in southern Ecuador to southern Peru and Bolivia (again, the eastern Andes).
Another case of convergent evolution is found in Pseudorhipsalis and Kimnachia. Although these species can appear similar to Rhipsalis and Lepismium (and even to Pfeiffera or Lymanbensonia) they are not at all closely related. Kimnachia is found at various locations from southern Mexico through Central America, down the eastern Andes to central Bolivia. Most species of Pseudorhipsalis are found in Central America -- many in Costa Rica -- while Pseudorhipsalis amazonica and its subspecies are found in Panama and northern Colombia, as well as ranging from southern Colombia through Ecuador to Peru, again in the eastern Andes.
Other epiphytic cacti are found in Mexico and Central America. A close relation to
Pseudorhipsalis and Kimnachia, the genus Epiphyllum is mostly found in Mexico and Central America. However, Epiphyllum phyllanthus and its subspecies have a larger distribution: they are found from southern Colombia and Venezuela, throughout Brazil, Guyana, Suriname, French Guyana and Paraguay, to eastern Peru and eastern Bolivia. In spite of the name, hybrid epicacti (which are commonly referred to as “epiphyllums”) are not related to the genus Epiphyllum. It appears instead hybrid epicacti are descended from members of the genus Disocactus, another relative.
Like Epiphyllum, Disocactus species occur in Mexico and Central America. Some hybrid
epicacti also have ancestors from Aporocactus (central and southern Mexico) and from some members of Selenicereus. Selenicereus has a large distribution, from Mexico and the Caribbean to Brazil and the northeastern part of South America. “Dragonfruit” varieties have been developed from Selenicereus ancestors.
One more small genus related to Selenicereus is Weberocereus. This genus is found mostly in Costa Rica and appears to be pollinated by bats.