Monday, May 15, 2006

The Origin of the Cactus Life-Form


The cactus form is often heralded as a striking example of the tight relationship between form and function in plants. A succulent, long-lived photosynthetic system allows cacti to survive periods of extreme drought while maintaining well-hydrated tissues.

Recent molecular phylogenetic work has confirmed that Pereskia, a genus that consists of 17 species of leafy shrubs and trees, is where the earliest cactus lineages began. Using field studies and environmental modeling, Drs. Edwards and Donoghue found that the Pereskia species already showed water use patterns that are similar to the leafless, stem-succulent cacti.


Pereskia and the Origin of the Cactus Life-Form. 2006. Erika J. Edwards and Michael J. Donoghue. The American Naturalist, volume 167.