MOODY, MICHAEL L* AND DONALD H LES. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269-3043. - Phylogenetic relationships in Myriophyllum (Haloragaceae).
Phylogenetic analyses of data from the plastid genes rbcL and
matK were conducted using parsimony and maximum likelihood
methods to assess the monophyly of the genus Myriophyllum
(Haloragaceae) and the relationships among the species.
Myriophyllum is an aquatic genus that consists of approximately
40 species with the greatest species diversity centered in Australia.
Relationships among many aquatic plants have been notoriously
difficult to assess due to their often convergent and highly plastic
vegetative morphology and structurally reduced flowers. All of these
factors have made it difficult to determine species limits and
relationships among Myriophyllum. MatK and rbcL
have been highly informative in delimiting relationships among species
of Myriophyllum. Our results indicate two well supported
clades in the genus. One clade consists predominantly of plants with
eight stamen flowers, the other predominately four stamen flowers. A
clade of North American endemics (Schindlerís Subgenus
Tessaronia) is also well supported. Currently, the cpDNA data
support a monophyletic Myriophyllum; although more inclusive
sampling among all genera in the family will be needed. Recently
acquired material of Haloragaceae genera and additional species of
Myriophyllum from Australia are currently being processed for
inclusion in expanded analyses.
Key words: aquatic plants, cpDNA, morphology, Myriophyllum, Phylogenetics