coxI intron phylogeny in flowering plants. Phylogenetic relationships among 49 angiosperm coxI intron DNA sequences inferred using ML (-lnL = 5938.60). Lineages shown in green are non-parasitic. Lineages in orange are mostly hemiparasitic, while those in red are holoparasitic. Bootstrap support values >50 and posterior probabilities > 0.8 are shown before and after the "/" respectively. Ordinal (or familial, if currently unplaced to order) classification is shown next to each taxon. Basal angiosperms and monocot orders are labeled in blue, rosid orders are labeled in purple, asterid orders are labeled in black, and Santalales are shown in yellow. General host plant preference for each parasitic plant lineage is shown next to each parasite (based on ref. # 3 and personal observations by TJB, JRM, and CWD). Overall phylogenetic relationships of the intron sequences are highly discordant with angiosperm phylogeny. Horizontal acquisition of the intron in parasites from their hosts does not seem likely because in no case is a highly supported relationship found between a parasite and any of its host lineages. Vertical acquisition of the intron in Cuscuta and Epifagus is supported by this tree because of the highly supported relationship found between these parasites and their close relatives.