Towards a molecular phylogeny of Apiaceae subfamily Apioideae:: additional information from nuclear ribosomal DNA ITS sequences

Evolutionary relationships among 116 representatives (80 genera) of Apiaceae (Umbelliferae) subfam. Apioideae were investigated by comparative sequencing of the two internal transcribed spacers of the 18S-26S nuclear ribosomal DNA repeat. The resultant phylogenies, inferred using maximum parsimony and neighbor-joining methods, clarified the relationships of several genera whose phylogenetic placements have heretofore been problematic. Comparisons between the phylogenies inferred and the distribution of several phytochemical (coumarins, flavonoids, and phenylpropenes) and morphological (stomates, pollen, and cotyledonary shape) characters were also made, revealing that many of these characters (like those morphological and anatomical characters of the fruit) are highly homoplastic. It is not surprising then that systems of classification of Apioideae based on these characters, particularly with regard to tribal and subtribal designations and relationships, are unsatisfactory. The results of recent serological investigations of the subfamily support several relationships proposed herein using molecular data.