The Eriocaulaceae is a pantropical family comprised of ten genera and approximately 1100 species. Members of the family are typically small annual or perennial, basally rosulate herbs. Flowers occur in compact involucrate capitula that superficially resemble inflorescences found within the Asteraceae, hence the description "Composites of the monocots." The Eriocaulaceae has traditionally been considered a natural group and allied with the Commelinales. The monophyly of the family has been supported by recent studies utilizing molecular data such as rbcL, although the close relationship to the Commelinales has been discarded and a closer relationship to the Poales proposed. In contrast to strong familial support, relationships within the family have proven difficult to determine. This is in part due to an overall lack of morphological variation and a reliance on minute floral characters. The majority of species are found within three large core genera, Eriocaulon (400 species), Paepalanthus (485 species) and Syngonanthus (200 species). Recent cladistic analyses of the family based on morphological and chemical characters have supported the monophyly of Eriocaulon and Syngonanthus, however Paepalanthus appears to be polyphyletic. To utilize a data set independent of morphology, we are sequencing the chloroplast trnT/L and trnL/F intergenic spacers as well as the 3 end of the ndhF gene. The trees generated from our data sets so far also support the monophyly of Eriocaulon and Syngonanthus and concur with the polyphyly of Paepalanthus. However, the molecular data differs from the morphological data for the placement of the smaller genera, and for the circumscription of the subgenera of Paepalanthus. For example, Lachnocaulon and Tonina have a sister group relationship and Blastocaulon appears to be polyphyletic. As more representative taxa are examined, a clearer picture of relationships within the family should emerge.

Key words: Commelinales, Eriocaulaceae, phylogeny