Phylogenetic relationships between Juncaceae and Cyperaceae: insights from rbcL sequence data

Abstract

Among the commelinid monocots, phylogenetic relationships involving Juncaceae and Cyperaceae have been difficult to resolve because of parallel and convergent evolution of morphological features. Using comparative sequencing of the chloroplast gene rbcL, hypotheses of relationships between these two families were tested. Sequences from 13 taxa were obtained for this study and analyzed using parsimony with 15 previously published sequences. Results of this analysis suggest that two genera of Juncaceae, Oxychloë and Prionium, are not closely related to the other genera of this family. Further, Cyperaceae appear to be more closely related to Juncaceae than to Poaceae, with which Cyperaceae are sometimes classified. In fact, Cyperaceae appear to be derived from within Juncaceae. The progenitor‐derivative relationship of Juncaceae and Cyperaceae suggested by this study reveals an additional example of paraphyletic families which presents a series of taxonomic dilemmas.