Intron distribution in relevant taxa.

*trnV introns in Cuscuta subg. Monogyna have deletions that may render them pseudogenes.Intron presence or absence is shown for Nicotiana tabacum (Solanaceae), Ipomoea purpurea and Cuscuta spp. (Convolvulaceae), and Epifagus virginiana (Orobanchaceae). Nicotiana, Ipomoea, and Cuscuta are classified in the order Solanales, while Epifagus virginiana is in the closely related order Lamiales. Subgeneric taxonomic classifications are listed for Cuscuta spp. Nicotiana intron distribution is typical of most angiosperms. “+” indicates intron present, “−” indicates precise intron loss from an intact gene, and “X” indicates loss of gene (and intron) from the plastid genome. Intron data for Nicotiana, Ipomoea, Cuscuta exaltata, Cuscuta reflexa, Cuscuta gronovii, Cuscuta obtusiflora, and Epifagus were gleaned from complete genome sequences available on genbank; all other data are based on PCR and PCR sequencing assays.