|Publication Type:||Journal Article|
|Year of Publication:||2010|
|Authors:||N. M. Nürk, Blattner F. R.|
|Keywords:||_nmn, biogeography, cladistic analysis, evolution, Hypericum, Phylogeny, St. John’s wort|
Hypericum is a worldwide distributed genus with almost 500 species, including the medically used apomictic species H. perforatum. It is one of the few large plant genera where alpha taxonomy is nearly completed. To conduct a formal cladistic analysis of the genus, we coded 89 morphological characters for all described taxa, and analyzed the data with parsimony and Bayesian methods. The obtained trees indicate Hypericum to be monophyletic, if the monotypic genus Santomasia is included, and Lianthus as the sister group. The arrangement of the remaining genera of Hypericaceae included in the analysis is in congruence with molecular phylogenies. Apomorphic characters supporting the relationships of the genera are pointed out. The cladistic analysis revealed four groups within Hypericum: a basal grade containing Mediterranean species and three big clades containing most of the diversity of the genus. The borders of the Mediterranean Sea as part of the late Tethys Ocean are hypothesized as a probable area of origin for the genus. As indicated in the presented tree, a shrubby habit appears to be the ancestral state within Hypericum from which trees and herbs evolved, and apomixis originated at least three times independently within the genus.
Cladistic analysis of morphological characters in Hypericum (Hypericaceae)