XVI International Botanical Congess

Phylogenetic origins of parasitic angiosperm lineages have been difficult to study using DNA sequences because plastid genes and 18SrDNA may be lost or evolve at very rapid rates making inferences uncertain. We undertook a large-scale sequencing study of conserved mtDNA genes present in all plants regardless of photosynthetic status. CoxI sequences were obtained from every major lineage of angiosperm including most hemi- and holo-parasites. Phylogenetic analysis unambiguously places 5 major parasitic groups within the context of angiosperm phylogeny. Three other parasitic lineages have uncertain placement, but we can reject previous hypotheses for their affinities. Relative rates of coxI evolution in the parasites are not greatly elevated, but accurate placement of all groups will require additional mtDNA sequences. To this end, we are accumulating atpA sequences to complement the coxI data.