Flora of North America species comparison

D. F. M. Brown (1964) believed that Woodsia oregana subsp. cathcartiana was confined to a single locality on the Minnesota-Wisconsin border. Recent chromosome counts, however, indicate that the tetraploid cytotype of Woodsia oregana is actually more widespread than the diploid subsp. oregana (M. D. Windham 1993). The inclusion of western U.S. collections within the definition of this taxon is supported by isozyme data that indicate some plants from Arizona and New Mexico are identical to those collected at the type locality of subsp. cathcartiana. In addition to crossing with subsp. oregana (see comments above), W. oregana subsp. cathcartiana hybridizes with W. neomexicana to produce sterile tetraploids of intermediate morphology. It also crosses with W. obtusa subsp. obtusa, resulting in the sterile tetraploid W. × kansana Brooks. F. S. Wagner (1987) has shown that W. oregana subsp. cathcartiana, not W. scopulina, hybridizes with W. ilvensis to form the sterile triploid W. × abbeae. Some morphologic evidence suggests that W. × maxonii may be a hybrid between subsp. cathcartiana and W. scopulina subsp. laurentiana; this hypothesis requires further testing. The difficulties involved with separating subsp. cathcartiana from certain plants of W. plummerae are discussed under that species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

The family Dryopteridaceae has been variously circumscribed; it is here delimited in a manner similar to that of R. M. Tryon and A. F. Tryon (1982) but with the inclusion of Nephrolepis. In many works, the family has gone under the illegitimate name Aspidiaceae. Some authorities define Dryopteridaceae more narrowly, to exclude Athyrium, Deparia, Diplazium, Cystopteris, and Gymnocarpium (Athyriaceae or Woodsiaceae), Woodsia (Woodsiaceae), Lomariopsis (Lomariopsidaceae), Nephrolepis (Nephrolepidaceae or Davalliaceae), Onoclea and Matteuccia (Onocleaceae), and Ctenitis and Tectaria (Tectariaceae). Characteristics holding Dryopteridaceae (as circumscribed here) together include the bilateral, monolete spores, often broadly winged perispore, absence of needlelike hairs, scaly stem and petiole bases, abaxial (nonmarginal) sori, base chromosome number of 40 or 41 (also 38 and 39 in Woodsia, 37 in Onoclea, 42 in Cystopteris), and usually indusiate sori. Loss of indusium, dimorphism, areolate venation, and reduced blade dissection have occurred repeatedly along many evolutionary lines in Dryopteridaceae, and in general these characteristics are often not very useful in delimiting genera or assessing intergeneric relationships.

In some genera, especially Phanerophlebia and Polystichum, the blade bears very narrow scales (sometimes called microscales) that resemble uniseriate hairs. These scales may be only one or two cells wide. Every intergradation exists between these filiform microscales and more typical, wider scales, and the two types are the same color, generally tan to brownish. Microscales are probably not homologous with true hairs, which may be either unicellular or multicellular, uncolored or sometimes reddish (as in Tectaria and Ctenitis), glandular (as in Woodsia) or not. Hairs in Dryopteridaceae, if present at all, are generally readily distinguishable from the needlelike, transparent ones found in Thelypteridaceae.

Genera ca. 60, species perhaps exceeding 3000 (18 genera, 79 species in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)