XVI International Botanical Congess

The higher-level classification of flowering plants is currently undergoing a revolution given the influx of DNA sequence data derived from the three subcellular genomes. Separate and combined analyses of nuclear, plastid, and mitochondrial genes are providing resolution of many long-standing questions regarding the placement of parasitic plants within the angiosperms. The hemiparasitic order Santalales will be used as an example to demonstrate how multiple DNA sequences, analyzed separately and in combination, can provide a biologically meaningful phylogeny. In contrast, a number of holoparasitic (nonphotosynthetic) plant families have proven intractable to phylogenetic analyses owing to gene losses and high substitution rates in typically conserved genes. Results derived from analyses of nuclear and mitochondrial small-subunit rDNA will be presented that provide compelling evidence for the placement of three of these families (in the broad sense) within angiosperms: Balanophoraceae, Hydnoraceae, and Rafflesiaceae.