Blastocaulon (Eriocaulaceae), a synonym of Paepalanthus: Morphological and molecular evidence

Generic circumscription in Eriocaulaceae has been based primarily on one to few floral characters and phylogenetic relationships within the family have only recently been explored in detail. Here, we present a morphological and phylogenetic study of Blastocaulon and Paepalanthus ser. Leptocephali, based on individual and combined datasets of the psbA-trnH plastid region and nuclear ITS. All results rejected the monophyly of Blastocaulon. Based on results and previous analyses, we propose the synonymization of Blastocaulon under Paepalanthus, the only morphological distinction between the two genera being the number of pollen-sacs. Reduction of pollen-sac number has occurred more than once in the evolution of Eriocaulaceae.