Phylogenetic Relationships inRhexia(Melastomataceae): Evidence from DNA Sequence Data and Morphology

In the large, pantropical family Melastomataceae, Rhexia is unique in having a temperate distribution. The species of Rhexia, the “meadow beauties,” are a common sight along roadsides and in open habitats in eastern North America, ranging from Nova Scotia to Florida and the West Indies and west to eastern Texas. In order to elucidate interspecific phylogenetic relationships in Rhexia, we analyzed four independently evolving data sets: the internal transcribed spacer (ITS) regions of ribosomal nuclear DNA, the chloroplast region trnC‐D, the nuclear gene that encodes chloroplast‐expressed glutamine synthetase (ncpGS), and 37 morphological characters. The ITS and chloroplast topologies differed in the phylogenetic positions of several taxa (R. lutea, R. nashii, and R. salicifolia), and for R. cubensis, R. lutea, R. nashii, R. parviflora, and R. salicifolia, we recovered multiple alleles of ncpGS, which is single copy in most species of Rhexia, indicating that these individuals may be of hybrid origin. Among ...