Polypodium scouleri
Polypodium appalachianum
coast, coast polypody, leather fern, leather-leaf fern, leather-leaf polypody, leathery polypody, leathery polypody fern, Scouler's polypody
Appalachian polypody, Appalachian rockcap fern, polypode des appalaches
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.
often whitish pruinose, slender, to 6 mm diam., acrid-tasting;
scales concolored to weakly bicolored, uniformly golden brown or slightly darker near apex, lanceolate, contorted distally, margins denticulate.
to 85 cm.
to 40 cm.
stout, to 3 mm diam.
slender, ± 1.5 mm diam.
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.
elongate-deltate, rarely oblong, pinnatifid, usually widest at or near base, to 9 cm wide, herbaceous to somewhat leathery;
rachis sparsely scaly to glabrescent abaxially, glabrous adaxially;
scales lanceolate-ovate, usually more than 6 cells wide.
oblong to linear, usually more than 12 mm wide;
margins entire to crenulate;
apex rounded to rarely broadly acute;
midrib glabrous adaxially.
linear to oblong, less than 8 mm wide, margins entire to crenulate;
apex acute to narrowly rounded;
midrib glabrous adaxially.
crowded against midrib, usually more than 3 mm diam., circular when immature.
midway between margin and midrib to nearly marginal, less than 3 mm diam., circular when immature.
usually less than 52 µm, rugose, surface projections less than 3 µm tall.
less than 52 µm, verrucose, projections less than 3 µm tall.
anastomosing, usually forming 1 row of areoles.
free.
absent.
present, usually more than 40 per sorus, heads densely covered with glandular hairs.
= 74, 111.
= 74.
Polypodium scouleri
Polypodium appalachianum
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.)
Polypodium appalachianum is a newly recognized species traditionally identified as the diploid cytotype of P. virginianum (A. M. Evans 1971; I. Manton and M. Shivas 1953). Because the tetraploid cytotype is an allopolyploid (C. H. Haufler and Wang Z. R. 1991), and the type specimen of P. virginianum is tetraploid (R. Cranfill and D. M. Britton 1983), the diploid is recognized here as a distinct species, P. appalachianum. Some collections of P. appalachianum can be difficult to distinguish from P. virginianum, but the latter species has spores averaging more than 52 µm, and P. appalachianum has spores less than 52 µm. Frequent hybridization between P. appalachianum and P. virginianum forms morphologically intermediate, triploid individuals with misshapen spores. Particularly confusing is the frequent occurrence of the triploid sympatric with only one parent or with neither parent nearby.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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