Chemotaxonomic studies on hybrids of Dryopteris in eastern North America

Sixty-nine specimens of Dryopteris were analyzed for phloroglucinols. Thirty-nine were referable to 9 sexual species and 30 were referable to 17 hybrid combinations. Ten hybrid combinations were analyzed for the first time. These are D. celsa × goldiana, D. celsa × clintoniana, D. assimilis × intermedia, D. campyloptera × intermedia, D. goldiana × intermedia, D. celsa × intermedia, D. assimilis × marginalis, D. campyloptera × marginalis, D. marginalis × spinulosa, and D. celsa × marginalis. Twenty-three naturally occurring hybrid taxa have now been analyzed and the use of the phloroglucinol system for systematics and evolutionary studies is assessed. Dryopteris marginalis and its hybrids have the most useful spectra of phloroglucinols for analysis. The hybrids in this group show the best additive spectra of the 23 hybrid taxa studied. Dryopteris marginalis, although a basic diploid species, is not considered to have given rise to derived alloploids.