| Biosystematic studies reveal that the New World species often included in the fern genus Cyrtomium (Dryopteridaceae) are distinct from their Asiatic counterparts, and should be segregated under the generic name Phanerophlebia. Restriction site analysis of chloroplast DNA mutations shows that Phanerophlebia and Cyrtomium were derived from different ancestral groups within Polystichum, a hypothesis supported by morphological, biogeographic, and life-history studies. Electrophoretic analysis of allozyme variation shows that these plants are all functionally outcrossers in nature, but the lack of inbreeding cannot be accounted for entirely by antheridiogen mediation, as some species do not produce or respond to this pheremone. Field studies and examination of the large number of recently collected specimens in herbaria allow refinement of the taxonomy of this New World genus and result in the finding that earlier classifications of the group emphasized characters now thought to be homoplasious. |
