botanyoneBroomrapes (Orobanche spp.) are a cosmopolitan genus of root holoparasites–non-photosynthetic angiosperms that obtain nutrients and energy by connecting to the roots of other plants. Using a phylogenetic study, based on mitrochondrial and ribosomal nuclear DNA markers, of western-hemisphere broomrapes, Schneider et al. demonstrate that extensive cryptic diversity is congruent with host association.
This highlights the important role that host-switching plays in the evolution and diversification of parasitic plants. Orobanche cooperi is a root parasite of Hymenoclea salsola and several other Astereaceae in the southwestern North American desert. Extensive morphological reduction of these plants masks the extensive diversity of western-hemisphere Orobanche. Most of these plants parasitize unique hosts, suggesting the likely role that host-switching plays in speciation.
