Journal: Systematic Botany
Volume: 27
Pages: 303-317


This is a molecular phylogenetic study of the group formerly known as Dryadeae, based on DNA sequences from the internal transcribed spacers, ITS, of nuclear ribosomal DNA and the trnL intron and the trnL-trnF intergenic spacer of the chloroplast. A total of 1.9 kb, for 26 ingroup species, were analyzed using parsimony and model-based Bayesian inference. Some clades are well supported by both data sets: the ingroup, with Fallugia as the sister to the rest of the clade; Sieversia in a strict sense; a clade consisting of all the herbaceous perennials, and some clades within this last group. Other clades, within the group of herbaceous perennials, differ between the analyses. The data sets in the present study do not support any previous circumscriptions of Geum nor any of the suggested segregate genera, except for the southern hemisphere Oncostylus. Morphological characters, notably fruit characters, mapped onto the combined tree show patterns of widespread parallel evolution and reversals—or possibly the effects of reticulations. Allopolyploidy has been suggested by previous workers and there are some indications of this in our results. Geum andicola appears in different well supported groups in the two separate analyses. This may be caused by inheritance of chloroplast DNA from one parental species and homogenization of ribosomal DNA from the other. Also, the intricate fruit type present in, for example, the type species of Geum, G. urbanum, appears to have evolved twice from progenitors with plumose styles. We propose the name Colurieae for this entire clade and the name Geinae for the group of herbaceous perennials.