UNWIN, MATTHEW M.1,2*, PAULO TAKEO SANO2, and LINDA E. WATSON1. 1Department of Botany, Miami University, Oxford, OH 45056 USA; 2Department de Botanica, Universidade de Sao Paulo, Sao Paulo 05422-970, Brazil. - Molecular Systematics of the Eriocaulaceae: evidence from chloroplast sequence data.
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