XVI International Botanical Congess

Cuphea, with 260 species, comprises thirteen sections that were defined by Koehne in 1903, based on one to a few key morphological characters. Nuclear ribosomal internal transcribed spacer (ITS) DNA sequences representing most of the thirteen sections were obtained to test their monophyly. Sections Brachyandra and Melvilla are polyphyletic, with members in at least three clades, suggesting that the floral characters that define them evolved more than once. Other sections, including Trispermum and Pseudocircaea, appear to be monophyletic. Three species with diporate pollen form a group, indicating that this state was derived from the triaperturate condition. Some groups correlate with geography, such as section Heterodon, which is restricted to North America.