Woodsia oregana subsp. cathcartiana
Woodsia oregana
cliff fern, Oregon cliff-fern, Oregon woodsia, western cliff fern, woodsie de l'Oregon
compact, erect to ascending, with few to many persistent petiole bases of unequal lengths;
scales often uniformly brown but at least some bicolored with dark central stripe and pale brown margins, narrowly lanceolate.
4–25 × 1–4 cm.
reddish brown to dark purple proximally when mature, not articulate above base, somewhat pliable and resistant to shattering.
linear-lanceolate to narrowly ovate, pinnate-pinnatifid or 2-pinnate proximally, sparsely to moderately glandular, never viscid;
glandular hairs with thin stalks and slightly expanded tips;
rachis with scattered glandular hairs and occasional hairlike scales.
ovate-deltate to elliptic, longer than wide, abruptly tapered to a rounded or broadly acute apex;
largest pinnae with 3–9 pairs of pinnules;
abaxial and adaxial surfaces glabrescent to moderately glandular, lacking nonglandular hairs or scales.
of narrow, usually filamentous segments, these uniseriate for most of length, composed of ± isodiametric cells, concealed by or slightly surpassing mature sporangia.
averaging 39–50 µm.
on pinnule margins irregular in shape, margins usually minutely dentate and appearing ragged;
adaxial epidermal cells averaging more than 120 µm. Spores averaging 45–50 µm. 2n = 152.
dentate, often shallowly lobed;
margins nonlustrous, thin, with occasional glands, lacking cilia, rarely with 1–2-celled translucent projections.
tips slightly (if at all) enlarged, barely visible adaxially.
Woodsia oregana subsp. cathcartiana
Woodsia oregana
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 variability and promiscuity of Woodsia oregana have been major sources of taxonomic difficulties in Woodsia, and more work will be necessary before relationships in this complex are fully resolved. As defined here, W. oregana comprises two subspecies that are chromosomally and biochemically distinct. In addition, the two taxa are nearly allopatric, with the diploid (subsp. oregana) confined to the Pacific Northwest and the tetraploid (subsp. cathcartiana) extending from the southwestern United States to eastern Canada. Isozyme studies indicate that subsp. cathcartiana is not an autotetraploid derived from known diploid populations of subsp. oregana, as was hypothesized by D. F. M. Brown (1964), and it may be more appropriate to recognize these taxa as distinct species. The morphologic features that distinguish these subspecies are very subtle, however, and they are associated primarily with differences in chromosome number. Until further systematic analyses are undertaken, these cytotypes should be maintained as subspecies of W. oregana.
Subspecies 2.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Spores averaging 39-45 µm; cells on pinnule margins regular in shape, margins appearing entire; adaxial epidermal cells averaging less than 120 µm. | subsp. oregana |
1. Spores averaging 45-50 µm; cells on pinnule margins irregular in shape, margins usually minutely dentate and appearing ragged; adaxial epidermal cells averaging more than 120 µm. | subsp. cathcartiana |
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