Morphological homoplasy and sectional polyphyly in Centaurea sect. Cynaroides and related taxa

Building natural classifications for genera with complex morphological variations such as Centaurea needs the support of molecular analysis and knowledge of morphological character diversification. Here we use parsimony and Bayesian analyses of nuclear ribosomal ITS sequences to gain insight into the sectional relationships and character evolution in Centaurea sections Chartolepis, Cheirolepis, Cynaroides, Grosheimia, Microlophus, Paraphysis, Phaeopappus, Plumosipappus, Pseudoserida, Pseudophaeopappus, Ptheracantha, Ptosimopappus, and Rhizocalathium, from Turkey. In particular, we increase sampling in Turkish endemic species of Centaurea sect. Cynaroides and related taxa. The new ITS sequences for 26 taxa from 48 locations are given. Sequences of 17 taxa are given here the first time. The phylogeny derived from ITS data provides a reasonably resolved and reasonably supported phylogenetic framework for the genus. Our analysis shows characters traditionally used in Centaurea taxonomy such as flower colour, appendage width, spine length, and pappus length evolved several times independently and show a lot of homoplasies. However, we can confirm the validity of character combinations for a reliable subgeneric classification of Centaurea.