XVI International Botanical Congess

A molecular phylogeny of the Lower Hamamelidae sensu Endress represented by 30 species from the Hamamelidaceae, Cercidiphyllaceae, Tetracentraceae, Eupteleaceae and Platanaceae is constructed by sequence analysis of nuclear ribosomal DNA internal transcribed spacers (ITS), and the monophyly of the Hamamelidaceae is circumscribed using parsimony analysis with the Tetracentraceae, Eupteleaceae and Platanaceae as the outgroup together or as outgroups respectively. All topologies are congruent and show that Cercidiphyllum japonicum is nested among hamamelidaceous species, and therefore Cercidiphyllum japonicum should be placed in the Hamamelidaceae. Moreover, the parsimony analysis supports the subfamilial status of Cercidiphyllum in the Hamamelidaceae, which is different from the present treatments of it as a separate family in the Trochodendales, Cercidiphyllales or Hamamelidales, but in concordance with the parsimony analysis of 18S ribosomal DNA sequences.