Polypodium hesperium
Polypodium calirhiza
western polypody, western polypody fern
licorice fern, nested polypody
occasionally whitish pruinose, slender to moderately stout, to 6 mm diam., acrid- to sweet-tasting: scales concolored, brown or slightly mottled, often darker near point of attachment, lanceolate, usually symmetric, margins entire to denticulate.
rarely whitish to glaucous, moderately stout to slender, to 8 mm diam., acrid- or slightly sweet-tasting;
scales concolored brown or slightly darker near point of attachment, lanceolate-ovate, symmetric, margins entire to erose.
to 35 cm.
to 70 cm.
slender, to 1.5 mm diam.
usually slender, to 3 mm diam.
oblong to lanceolate-ovate, occasionally deltate, pinnatifid, usually widest at or near middle, to 7 cm wide, herbaceous to somewhat leathery;
rachis sparsely scaly to glabrescent abaxially, glabrous adaxially;
scales linear-lanceolate, usually less than 6 cells wide.
lanceolate-ovate to oblong, pinnatifid, widest below middle or occasionally at base, to 16 cm wide, leathery to herbaceous;
rachis sparsely scaly to glabrescent abaxially, puberulent adaxially;
scales lanceolate-ovate, usually more than 3 cells wide.
oblong to linear-lanceolate, less than 12 mm wide;
margins entire to crenulate or obscurely serrate;
apex obtuse to acute;
midrib glabrous adaxially.
linear-lanceolate to oblong, usually less than 15 mm wide;
margins conspicuously serrate;
apex obtuse to acute;
midrib puberulent adaxially.
midway between margin and midrib, less than 3 mm diam., oval when immature.
midway between margin and midrib or slightly closer to midrib, usually less than 4 mm diam., oval when immature.
more than 58 µm, rugose to verrucose or tuberculate, surface projections commonly less than 3 µm.
more than 58 µm, verrucose, surface projections less than 3 µm.
free.
weakly to moderately anastomosing, some to many segments lacking areoles.
absent.
absent.
= 148.
= 148.
Polypodium hesperium
Polypodium calirhiza
Using morphologic and chromosomal data, F. A. Lang (1971) proposed that Polypodium hesperium originated through allotetraploidy involving P. glycyrrhiza and P. amorphum, a hypothesis recently supported by electrophoretic studies (C. H. Haufler, M. D. Windham, and E. W. Rabe, unpublished). Variations in spore surface morphology and banding patterns observed in isozyme studies indicate that P. hesperium may have originated more than once from different individuals of the same species. Some collections of P. hesperium can be mistaken for P. glycyrrhiza, but the latter species is easily distinguished by its pubescent rachises, linear blade scales, and smaller spores (less than 58 µm). Although P. amorphum has sporangiasters and P. hesperium lacks them, misshapen sporangia in P. hesperium can mimic these distinctive soral structures. Therefore, it is often necessary to use a combination of soral, stem scale, and blade scale features (discussed in the key) to separate P. hesperium from P. amorphum. Hybridization occurs between P. hesperium and each of its progenitor diploids to form triploid individuals with misshapen spores (F. A. Lang 1971). Rare, sterile, tetraploid hybrids with P. saximontanum have also been detected (M. D. Windham, unpublished).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Although originally considered a cytotype of Polypodium californicum, P. calirhiza is an allotetraploid involving P. californicum and P. glycyrrhiza (S. A. Whitmore and A. R. Smith 1991) and therefore should be treated as a distinct species. Some individuals of P. calirhiza can be difficult to distinguish from the two parental species (see comments under P. californicum and P. glycyrrhiza); most collections can be identified based on a combination of blade shape, venation pattern, spore size, and geographic distribution. Polypodium calirhiza hybridizes with P. glycyrrhiza to produce sterile triploid plants with misshapen spores.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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