XVI International Botanical Congess

Current knowledge of early lycophyte evolution indicates the earliest occurrence is Late Silurian for zosterophylls and basal lycopsids. New data about their construction, growth habit, rooting structures, and reproduction mostly supports current hypotheses of relationship and evolutionary patterns. Basal groups still are poorly understood. Some Pragian Chinese fossils with leaf-like appendages are problematic because of uncertainties over homology. New data about Protolepidodendraleans suggests more diversity in the Early and Middle Devonian than previously known. Elucidation of stem lycophytes and some zosterophylls, transition from herbaceous to arborescent habit, evolution of rooting types, changes in reproductive syndromes, and clarification of relationships between Devonian and younger taxa are areas in need of additional research.