Polypodium virginianum
Polypodium appalachianum
common polypody, polypode de virginie, rock polypody, tripes-de-roches
Appalachian polypody, Appalachian rockcap fern, polypode des appalaches
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.
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 40 cm.
to 40 cm.
slender, to 2 mm diam.
slender, ± 1.5 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.
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, less than 8 mm wide;
margins entire to crenulate;
apex rounded to 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.
midway between margin and midrib to nearly marginal, less than 3 mm diam., circular when immature.
midway between margin and midrib to nearly marginal, less than 3 mm diam., circular when immature.
more than 52 µm, tuberculate, surface projections more than 3 µm tall.
less than 52 µm, verrucose, projections less than 3 µm tall.
free.
free.
present, usually less than 40 per sorus, heads covered with glandular hairs.
present, usually more than 40 per sorus, heads densely covered with glandular hairs.
= 148.
= 74.
Polypodium virginianum
Polypodium appalachianum
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.)
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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