My research has focused on the evolutionary relationships of the pteridophytes as indicated by the fossil record and through molecular analyses, with the ultimate goal of documenting times of appearance of groups and the role of pteridophytes in the environments of the past, as well as the relationships of the extant and extinct taxa.  The suggested phylogenies which best stand the tests of time are supported by fossil evidence.  My work has emphasized the ferns of the Cretaceous Age using the local Potomac Group and the Dakota Group. Other studies have included the Lower Carboniferous, Devonian, and Triassic. In addition recent fern groups studied include the genera Anemia, Schizaea, and Elaphoglossum. Much of the work is now revisionary due to improved techniques of analysis such as molecular analysis, electron microscopy and computer analysis of characters.  Gradually this work is leading to a view of more primitive families in the lower Cretaceous probably in the role of ground covers followed by newer families in the later Cretaceous in a less dominant position in the environment. Recent work has focused on the integration of all data: fossil, morphological and molecular, to elucidate the position and importance of the primitive families of ferns.