XVI International Botanical Congess
Relationships among basal angiosperm groups were investigated in the context of a larger phylogenetic analysis of the angiosperms. Analyses based on multiple genes reconstructed a grade of monosulcates at the base of the angiosperm tree. Amborellaceae, Nymphaeaceae, and a clade of Austrobaileyaceae, Illiciaceae, and Schisandraceae are successive sisters to all other angiosperms. The remaining monosulcates, except Ceratophyllum, which is the sister to the eudicots, form a weakly-supported clade that comprises six strongly-supported subclades: Chloranthaceae, Piperales, monocots, Laurales, Winteraceae/Canellaceae, and Magnoliales. Relationships among these six clades are not strongly supported. To compensate for homoplasy at these deep levels, we performed a compartmentalized analysis.