Polypodium virginianum
Polypodium scouleri
common polypody, polypode de virginie, rock polypody, tripes-de-roches
coast, coast polypody, leather fern, leather-leaf fern, leather-leaf polypody, leathery polypody, leathery polypody fern, Scouler's polypody
often whitish pruinose, slender, to 6 mm diam., acrid-tasting;
scales weakly bicolored, lanceolate, contorted distally, base and margins light brown, sometimes with dark central stripe, margins denticulate.
conspicuously whitish pruinose, stout, 3–12 mm diam., bland to slightly sweet-tasting;
scales concolored to weakly bicolored, uniformly dark brown or with pale margins and base, lanceolate, symmetric, margins denticulate.
to 40 cm.
to 85 cm.
slender, to 2 mm diam.
stout, to 3 mm diam.
oblong to narrowly lanceolate, pinnatifid, usually widest near middle, occasionally at or near base, to 7 cm wide, somewhat leathery;
rachis sparsely scaly to glabrescent abaxially, glabrous adaxially;
scales lanceolate-ovate, usually more than 6 cells wide.
ovate-lanceolate, pinnatifid, usually widest just above base, to 27 cm wide, stiff and leathery;
rachis sparsely scaly to glabrescent abaxially, glabrous adaxially;
scales bicolored, ovate-lanceolate, much more than 6 cells wide.
oblong, less than 8 mm wide;
margins entire to crenulate;
apex rounded to broadly acute;
midrib glabrous adaxially.
oblong to linear, usually more than 12 mm wide;
margins entire to crenulate;
apex rounded to rarely broadly acute;
midrib glabrous adaxially.
midway between margin and midrib to nearly marginal, less than 3 mm diam., circular when immature.
crowded against midrib, usually more than 3 mm diam., circular when immature.
more than 52 µm, tuberculate, surface projections more than 3 µm tall.
usually less than 52 µm, rugose, surface projections less than 3 µm tall.
free.
anastomosing, usually forming 1 row of areoles.
present, usually less than 40 per sorus, heads covered with glandular hairs.
absent.
= 148.
= 74, 111.
Polypodium virginianum
Polypodium scouleri
Traditionally, two cytotypes have been recognized within Polypodium virginianum (I. Manton and M. Shivas 1953). Recent research has demonstrated that the tetraploid cytotype, which properly bears the name P. virginianum (R. Cranfill and D. M. Britton 1983), is an allopolyploid produced by hybridization between the diploid cytotype (here called P. appalachianum) and P. sibiricum (C. H. Haufler and M. D. Windham 1991; C. H. Haufler and Wang Z. R. 1991). Although sometimes similar to its diploid parents in overall leaf morphology, P. virginianum has consistently larger spores, typically more than 52 µm (see additional comments under P. appalachianum and P. sibiricum). Frequent hybridizations between P. virginianum and P. appalachianum form morphologically intermediate, triploid individuals with misshapen spores. Sterile triploids also result from hybridization between P. virginianum and P. sibiricum.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The distinctive Polypodium scouleri has occasionally been assigned to the genus Goniophlebium because of its anastomosing venation and conspicuous areoles. Its venation pattern can be quite variable, however, and cannot be used as the sole feature distinguishing P. scouleri from P. californicum. Combining venation characteristics with others provided in the key distinguishes it clearly from its congeners in Polypodium. Some evidence suggests that P. scouleri hybridizes with P. californicum (S. A. Whitmore, unpubl.). I. Manton (1951) reported diploid and triploid cytotypes for P. scouleri, and variation in spore size suggests that the species may also include tetraploid populations.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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