Polypodium amorphum
irregular polypody, irregular polypody fern, Pacific polypody
often whitish pruinose, slender, to 6 mm diam., acrid-tasting;
scales weakly bicolored, lanceolate, contorted distally, bases and margins light brown, sometimes with dark central stripe, margins often coarsely dentate.
to 30 cm.
slender, to 1.5 mm diam.
oblong to rarely deltate, pinnatifid, usually widest near middle, occasionally at or near base, to 4 cm wide, somewhat leathery;
rachis sparsely scaly to glabrescent abaxially, glabrous adaxially;
scales lanceolate-ovate, usually more than 6 cells wide.
oblong, less than 12 mm wide;
margins entire to crenulate;
apex rounded to broadly acute;
midrib glabrous adaxially.
midway between margin and midrib to nearly marginal, less than 3 mm diam., circular when immature.
more than 58 µm, rugose to verrucose, surface projections less than 3 µm tall.
free.
present, usually less than 40 per sorus, heads covered with glandular hairs.
= 74.
Polypodium amorphum
The diploid Polypodium amorphum is one of the progenitors of allotetraploid P. hesperium, and these two species are occasionally sympatric. Although P. amorphum can be mistaken for P. hesperium, consistent differences exist for separating these two species (see comments under P. hesperium). Hybridization between P. amorphum and P. hesperium results in triploid individuals with misshapen spores (F. A. Lang 1971).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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