The biology of non-weedy hemiparasiticOrobanchaceae: Synthesis and perspectives

This paper gives an overview of current research into the biology of hemiparasiticOrobanchaceae, formerly part of theScrophulariaceae. It is based on presentations and discussions that took place during the First International Symposium on non-weedy hemiparasiticOrobanchaceae in April 2004 in Wageningen. Aspects such as taxonomy and evolution, ecophysiology, population and restoration ecology are discussed, thus identifying challenges for future research. Hemiparasites have very different life histories, and the robust molecular phylogeny will now permit testing hypotheses regarding the evolution of these life histories, degree of parasitism and host specialization. In a number of genera, evolution is in full swing, leading to taxonomical complications, but at the same time offering opportunities for phylogeographical research. In ecophysiology, the challenge is to better understand what makes a good host and to investigate further the chemical signals emitted by the host and their use in regulating parasite development. Finally, the results of sowing hemiparasites to speed up the restoration of nutrient-poor grasslands are still very variable, and we need a more thorough understanding of the factors influencing population dynamics, which should also enable us to devise better management plans for threatened hemiparasitic species.