XVI International Botanical Congess

Piper is one of the largest and least studied genera of angiosperms. As part of an ongoing study of floral evolution and systematics of Piper, the ITS region was sequenced for 46 species of Piper and 4 outgroups. Parsimony analyses suggest Piper is monophyletic, with subgenus Sarcorhachis positioned as sister to the remaining sample of Piper. Although the relationships among the major clades of Piper were not well resolved, the monophyly of many traditional groups was confirmed (Macropiper, Macrostachys , Piper, Pothomorphe , Radula, and Sarcorhachis), whereas Steffensia and Trianaeopiper appear to be polyphyletic. The polyphyly of Steffensia suggests that the floral structure of this subgenus is plesiomorphic within Piper. The polyphyly of Trianaeopiper suggests that the axillary inflorescence, a defining character of this subgenus, has multiple origins.