This research has examined the phylogenetic relationship between the questionable Athyrium pycnocarpon and the valid Athyrium thelypteroides. Classical taxonomic data were reported to illustrate the sources of confusion in the phylogenetic positioning of the fern in question. Chromatographic analyses of biochemical secondary constituents were reported. Descending paper chromatograms, ascending thinlayer chromatograms and cellulose-acetate electrophoretograms were the three analytical tools used to develop the secondary compounds. Ultraviolet light and ninhydrin visualization of the separated secondary constituents produced characteristic spotting patterns. On the basis of the close similarities of all patterns between the Athyrium pycnocarpon and Athyrium thelypteroides, it was concluded that the Athyrium pycnocarpon is unquestionably a member of the Athyrium complex.Ball State UniversityMuncie, IN 47306