The most recent molecular phylogenetic treatment of Orobanchaceae and taxa traditionally treated as hemiparasitic Scrophulariaceae is the following:
OLMSTEAD, R. G., C. W. DEPAMPHILIS, A. D. WOLFE, N. D. YOUNG, W. J. ELISENS, AND P. J. REEVES. 2001. Disintegration of the Scrophulariaceae. American Journal of Botany 88: 348-361.
This paper discusses the results of analyses using three chloroplast genes (rbcL, ndhF and rps2) for 39 genera of Scrophulariaceae s. lat. In terms of parasitic members, all were placed within Orobanchaceae that included Buchnereae and Rhinantheae (Scrophulariaceae) and the conventional Orobanchaceae. Click HERE to view the tree from that publication.
Shown below is a phylogenetic reconstruction of parasitic Scrophulariaceae (part of strict consensus tree) based on a parsimony analysis of the gene rps2 - a ribosomal protein gene found in the chloroplast genome. The arrow indicates that within Scrophulariaceae, parasitism was derived only once, hence the parasites are monophyletic. This parasite clade also includes genera traditionally assigned to Orobanchaceae. Although parasitism was gained only once, these data indicate that the loss of photosynthesis has occurred on at least five occassions. Nonphotosynthetic holoparasites are indicated by thick yellow lines and yellow lettering. Species with green lettering are photosynthetic hemiparasites. Only one nonparasitic scroph (Lindenbergia) is shown as an outgroup, however, 14 other nonparasitic species were analyzed in the original publication. The numbers above the nodes (bootstrap values) indicate how well-supported the clade is; nodes without values were supported in less than 50% of the replications. A more detailed discussion of this analysis can be found in dePamphilis, C. W. N. D. Young, and A. D. Wolfe (1997; Evolution of plastid gene rps2 in a lineage of hemiparasitic and holoparasitic plants: many losses of photosynthesis and complex patterns of rate variation. Proc. Natl. Acad. Sci. U.S.A. 94: 7367-7372).
The tree below is a phylogenetic reconstruction of parasitic Scrophulariaceae (part of strict consensus tree) based on a parsimony analysis of the gene rbcL - a photosynthetic gene found in the chloroplast genome. As with rps2 above, this gene also indicates that parasitism evolved only once in Scrophulariaceae, that this family includes genera traditionally assigned to Orobanchaceae, and that the loss of photosynthesis has occurred on several occassions. Nonphotosynthetic holoparasites are indicated by thick yellow lines and yellow lettering. Species with green lettering are photosynthetic hemiparasites. Species marked with a Greek letter psi have pseudogenes for rbcL. Only one nonparasitic scroph (Paulonia) is shown as an outgroup, however, 15 other nonparasitic species were analyzed in the original publication. The numbers above the nodes (bootstrap values) indicate how well-supported the clade is; nodes without values were supported in less than 50% of the replications. This work was conducted by Dr. A. Wolfe in collaboration with Dr. C. dePamphilis. A more detailed discussion of this analysis can be found in Nickrent, D. L., J. R. Duff, A. E. Colwell, A. D. Wolfe, N. D. Young, K. E. Steiner & C. W. dePamphilis. Molecular phylogenetic and evolutionary studies of parasitic plants in D. E. Soltis, P. S. Soltis, & J. J. Doyle (Editors), Molecular Systematics of Plants. Chapman and Hall, New York. Due out in 1998.
SIUC / College of Science / Parasitic Plant Connection
URL: http://www.parasiticplants.siu.edu/Relation-Scroph.html
Last updated: 27-Mar-02 / dln