Research in my laboratory focuses on the evolution of early land plants, and encompasses the study of fossils dating from the Silurian to the Early Carboniferous. During this time period, the fossil record indicates that all major plant organs (e.g. roots, leaves, seeds, secondary tissues) except flowers appeared. Given current phylogenetic analyses of fossil and living plants, it is evident that some of these structures arose more than once in different lineages (homoplasy) (Gensel, 2008).
We are now engaged in a detailed study of a variety of zosterophyll and lycopsid forms to help elucidate early diversification of the lycophyte clade of vascular plants (Gensel 1991, 1992; Gensel and Berry, 2001; Gensel an dKasper, 2005; Gensel and Albright, 2006; Gensel and Pigg, 2010) and are developing a hypothesis about the evolution of rooting structures (possibly involving heterochrony) (Gensel et al. 2001; Gensel and Berry 2001).
Our study of plants now regarded as part of the second major clade of early vascular plants (the euphyllophytes), and the one that leads to seed plants, has provided considerable evidence of possible steps in the early evolution of leaves (Gensel, 1979; 1984; Trant and Gensel, 1985; Gensel ms in prep). With colleagues, I have been studying the ultrastructure of spores produced by plants from the above clades in an attempt to determine if there are taxonomic signatures in wall organization that may aid in determining possible affinities of dispersed spore types or to deduce evolutionary patterns in spores within clades (Wellmean and Gensel, 2004; Taylor et al, 2009; Taylor et al, submitted).
A synthetic overview of the diversity of early land plants, and implications for evolutionary events, patterns or processes was published in Plant Life in the Devonian (Gensel and Andrews 1984). I also co-edited, with D. Edwards, a book entitled Plants Invade the land-Evolutionary and Environmental Perspectives (2001) which includes analyses, based on plant fossils and geological data, of the earliest phases of the history of plants.