Phylogeny and biogeography of Orobanchaceae

Orobanchaceae, as it is currently defined, includes all levels of parasitic ability ranging from nonparasitic (Lindenbergia) to facultative and obligate hemiparasites to obligate holoparasites. Several genera are of economic importance as crop weeds and have been studied by scientists interested in developing methods of control, but most genera have not been studied in a comparative framework. In this study we have used ITS sequence data to build a phylogenetic framework with which to examine previous systematic hypotheses of relationships among genera, and biogeographic hypotheses of either a Cretaceous, Gondwanan or mid-Tertiary, Laurasian origin of the family. A single-most parsimonious ITS tree was produced from a combined data set of nucleotides and gap characters. Our results support the current classification of Orobanchaceae and a hypothesis of a mid-Tertiary, Laurasian origin of the family.