Difference between revisions of "Polypodium sibiricum"

Revision as of 18:55, 24 September 2019

Copyright: Flora of North America Association

Stems often whitish pruinose, slender, to 6 mm diam., acrid-tasting; scales concolored to weakly bicolored, uniformly dark brown, often lighter near base, lanceolate, contorted distally, margins denticulate. Leaves to 25 cm. Petiole slender, to 1 mm diam. Blade oblong-linear, pinnatifid, usually widest at or near middle, to 4 cm wide, somewhat leathery; rachis sparsely scaly to glabrescent abaxially, glabrous adaxially; scales lanceolate-ovate, usually more than 6 cells wide. Segments oblong, less than 7 mm wide; margins entire to crenulate; apex rounded to broadly acute; midrib glabrous adaxially. Venation free. Sori midway between margin and midrib to nearly marginal, less than 3 mm diam., circular when immature. Sporangiasters present, less than 40 per sorus, heads normally without glandular hairs. Spores less than 52 µm, tuberculate with tubercles, surface projections more than 3 µm tall. 2n = 74.

Phenology: Sporulating summer–early fall.
Habitat: Cracks and ledges on rock outcrops, on a variety of substrates including granite and dolomite
Elevation: 100–1000 m

Greenland, Alta., B.C., Man., N.W.T., Ont., Que., Sask., Yukon, Alaska, n Asia.

Discussion

This boreal diploid has traditionally been identified as Polypodium virginianum (T. M. C. Taylor 1970; F. A. Lang 1971), but recent investigations indicate that it is conspecific with the eastern Eurasian species P. sibiricum (C. H. Haufler and M. D. Windham 1991). The sporangiasters of P. sibiricum normally lack glands, but some collections have sporangiasters with a few glandular hairs. Although such collections could be misidentified, the spores of P. sibiricum are less than 52 µm and clearly distinguish it from P. virginianum, P. amorphum, and P. saximontanum. Hybridization occurs between P. sibiricum and P. virginianum where these species overlap in Canada, forming triploid individuals with misshapen spores (C. H. Haufler and Wang Z. R. 1991).

Selected References

None.

Lower Taxa