Polypodium hesperium
Polypodium triseriale
western polypody, western polypody fern
anglevein fern
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.
not whitish pruinose, slender to stout, 5–15 mm diam., taste unknown;
scales brown, ovate-acuminate, symmetric, somewhat to strongly clathrate, margins somewhat lighter, entire.
to 35 cm.
to 90 cm.
slender, to 1.5 mm diam.
slender to stout, to 7 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.
broadly ovate, 1-pinnate at base, widest at or near base, to 60 cm wide, papery to almost leathery;
rachis glabrous abaxially and adaxially.
oblong to linear-lanceolate, less than 12 mm wide;
margins entire to crenulate or obscurely serrate;
apex obtuse to acute;
midrib glabrous adaxially.
(pinnae) linear to oblong, apex acuminate;
proximal segments stalked to nearly sessile, distal ones slightly narrowed but broadly adnate at base, less than 35 mm wide;
margins entire or slightly wavy;
apex acute;
midrib glabrous adaxially.
midway between margin and midrib, less than 3 mm diam., oval when immature.
in 1–3 parallel rows on both sides of costa, 0.5–3 mm diam., circular when immature.
more than 58 µm, rugose to verrucose or tuberculate, surface projections commonly less than 3 µm.
less than 58 µm, verrucose, with surface projections less than 3 µm.
free.
anastomosing with a regular series of 2–5 rows of areoles on both sides of costae.
absent.
absent.
= 148.
= 148.
Polypodium hesperium
Polypodium triseriale
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P. amorphum, a hypothesis recently supported by electrophoretic studies (C. H. Haufler, M. D. Windham, and E. W. Rabe, unpublished).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.)
Commonly found in montane tropical rainforests, the epiphytic Polypodium triseriale is quite distinct from and probably only distantly related to other North American members of Polypodium. It seems likely that spores are occasionally blown into southern Florida, probably from the West Indies, and plants develop as naturalized populations.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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