Christmas Science 5: Christmas Cactus

In the run up to Christmas, Communicate Science offers you 20 Christmas Science Facts. We'll post one every day until the 25th December.

Christmas Cactus
Lots of people will be quite familiar with the bright purple flowers and prickly looking foliage of the Christmas Cactus (Schlumbergera truncata). It is widely cultivated and sold as house plants, particularly around this time of year.

There are in fact five species in the genus, all from South America. Four, including S. truncata, are native to the Atlantic Forest of Rio de Janeiro and adjacent parts of Sao Paulo, while the remaining species is geographically isolated from the rest.

S. kautskyi is on the Red List of critically endangered plants and is found in just two small mountain localities, both of which are in an area where recent residential developments are causing significant changes. The species, discovered in 1986, is under increasing pressure in the wild and just small fragments of its home range remain.

This endangered species is very similar to the Christmas Cactus with which we are familiar, with its flattened stem segments and sharply pointed edges. The flowers of the cultivated species however, are much larger than its endangered cousin.

Source: RBG Kew, Plant; J. Marinelli (Ed)