Belgian Journal of Botany vol:137 issue:2 pages:125-139
Triplostegia, a perennial herb from Southeast Asia with a distinctive double epicalyx, is controversial with respect to its rank and phylogenetic relationships. Since different lines of morphological evidence indicate that Triplostegia shows affinities to both Valerianaceae and Dipsacaceae, the genus has been included in either of the two families. In addition, some authors have accepted Triplostegiaceae as a distinct monogeneric family. Maximum parsimony analysis based on new ndhF sequences showed Triplostegia to be a relatively strongly supported sister to Dipsacaceae. Additionally, trees were constructed from available rbcL data separately and in combination with ndhF. The topology of the combined molecular cladogram is in agreement with the ndhF phylogeny. Analysis based on a morphological matrix was conducted and resulted in Triplostegia as a strongly supported sister of Valerianaceae; a similar position was obtained from the total combined analysis. Different scenarios for the origin of the double epicalyx are presented.