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western polypody, western polypody fern

Appalachian polypody, Appalachian rockcap fern, polypode des appalaches

Stems

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.

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.

Leaves

to 35 cm.

to 40 cm.

Petiole

slender, to 1.5 mm diam.

slender, ± 1.5 mm diam.

Blade

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.

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.

Segments

oblong to linear-lanceolate, less than 12 mm wide;

margins entire to crenulate or obscurely serrate;

apex obtuse to acute;

midrib glabrous adaxially.

linear to oblong, less than 8 mm wide, margins entire to crenulate;

apex acute to narrowly rounded;

midrib glabrous adaxially.

Sori

midway between margin and midrib, less than 3 mm diam., oval when immature.

midway between margin and midrib to nearly marginal, less than 3 mm diam., circular when immature.

Spores

more than 58 µm, rugose to verrucose or tuberculate, surface projections commonly less than 3 µm.

less than 52 µm, verrucose, projections less than 3 µm tall.

Venation

free.

free.

Sporangiasters

absent.

present, usually more than 40 per sorus, heads densely covered with glandular hairs.

2n

= 148.

= 74.

Polypodium hesperium

Polypodium appalachianum

Phenology Sporulating summer–fall. Sporulating summer–fall.
Habitat Cracks and ledges on cliffs, on a variety of noncalcareous substrates, rarely on limestone Cliffs and rocky slopes, on a variety of substrates
Elevation 300–3500 m. (1000–11500 ft.) 0–1800 m (0–5900 ft)
Distribution
from FNA
AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; BC; Mexico in Chihuahua; Baja California
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; CT; DC; DE; GA; KY; MA; MD; ME; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WV; NB; NF; NS; ON; PE; QC
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

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.)

Source FNA vol. 2. FNA vol. 2.
Parent taxa Polypodiaceae > Polypodium Polypodiaceae > Polypodium
Sibling taxa
P. amorphum, P. appalachianum, P. californicum, P. calirhiza, P. glycyrrhiza, P. saximontanum, P. scouleri, P. sibiricum, P. triseriale, P. virginianum
P. amorphum, P. californicum, P. calirhiza, P. glycyrrhiza, P. hesperium, P. saximontanum, P. scouleri, P. sibiricum, P. triseriale, P. virginianum
Synonyms P. prolongilobum, P. vulgare subsp. columbianum, P. vulgare var. columbianum, P. vulgare var. hesperium
Name authority Maxon: Proc. Biol. Soc. Wash. 13: 200. (1900) Haufler & Windham: Amer. Fern J. 81: 18. (1991)
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