Aichryson is a small genus of annual or perennial herbs, comprising approximately 13 species. The genus is endemic to Macaronesia (Azores, Canary, Cape Verde, Madeira, and Salvage Islands), with the center of diversity occurring on the Canary Islands. Previous phylogenetic analyses of the Macaronesian Crassulaceae indicate that Aichryson is a well-supported monophyletic group and is sister to a clade comprising Monanthes and Aeonium. However, phylogenetic relationships within the genus have not yet been thoroughly investigated. To resolve relationships within Aichryson, DNA sequences were generated from the nuclear ribosomal internal transcribed spacers regions (ITS1 and ITS2) as well as from three cpDNA regions (trnL-trnF, psbA-trnH, and matK). Separate parsimony analyses were conducted for the cpDNA and nuclear data sets. Congruence tests conducted on each of these data sets and the resulting topologies revealed no “hard incongruences”; therefore, the data were combined and reanalyzed. Parsimony analyses of the combined data recover a well-resolved topology with many relationships receiving high bootstrap support. Although typically herbaceous in habit, two members of the genus display a woody growth form. Our preliminary analyses indicate that woodiness is a derived character in Aichryson that appears to have evolved a single time. The estimate of phylogeny is also used to reassess the currently accepted classification of the genus.

Key words: Aichryson, Character evolution, Crassulaceae