2005/07/01 by Erika J. Edwards, Reto Nyffeler, Michael J. Donoghue · 5 citations
Agricultural and Biological Sciences · #Botanical Research and Applications #Plant Diversity and Evolution #Botany, Ecology, and Taxonomy Studies
paper · doi:10.3732/ajb.92.7.1177
openalex publication_date 2005/07/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/15
The cacti are well-known desert plants, widely recognized by their specialized growth form and essentially leafless condition. Pereskia, a group of 17 species with regular leaf development and function, is generally viewed as representing the "ancestral cactus," although its placement within Cactaceae has remained uncertain. Here we present a new hypothesis of phylogenetic relationships at the base of the Cactaceae, inferred from DNA sequence data from five gene regions representing all three plant genomes. Our data support a basal split in Cactaceae between a clade of eight Pereskia species, centered around the Caribbean basin, and all other cacti. Two other Pereskia clades, distributed mostly in the southern half of South America, are part of a major clade comprising Maihuenia plus Cactoideae, and Opuntioideae. This result highlights several events in the early evolution of the cacti. First, during the transition to stem-based photosynthesis, the evolution of stem stomata and delayed bark formation preceded the evolution of the stem cortex into a specialized photosynthetic tissue system. Second, the basal split in cacti separates a northern from an initially southern cactus clade, and the major cactus lineages probably originated in southern or west-central South America.