XVI International Botanical Congess

Complex structures in modular organisms such as pteridophytes are composed of simple ones and homology assessments need to be addressed at the level of organization. Homology assessments are compared on anatomical level and morphological level of the roots, leaves, and indumentum of pteridophytes. Recent phylogenetic analyses offer the possibility to test hypothetical homologies, which in turn can provide new insights. The homology and origin of various organs have been the subject of controversial discussions in the past. It will be shown here that a phylogenetic approach can help to resolve some of these homology questions that have centered on: the sporangial position in different lineages of pteridophytes, the organs of water ferns, and the origin of roots.