From the Greek, hesperus, meaning of the West.
Rhizome: creeping, branching, slender, whitish waxy sometimes, about 5 mm diameter, acrid to sweet flavored, scales lanceolate, brown or slightly mottled, often darker near point of attachment.
Frond: 25 cm high by 7 cm wide, evergreen, monomorphic, blade/stipe ratio: 2:1.
Stipe: jointed at base, straw-colored, glabrous or scattered with thin light-brown scales, vascular bundles: 3.
Blade: pinnatifid, oblong, usually widest near middle, occasionally at or near base, herbaceous, ligt to yellowish-green, glabrous above, sometimes a few scales below.
Pinnae: 8 to 12 pair, oblong, less than 3 cm long, tips obtuse to acute; margins entire to crenulate; veins free, hard to see.
Sori: oval when immature, round later, less than 3 mm diam., midway between margin and midrib to nearly marginal; on all but the lowest pinnae of fertile fronds, indusium: absent, sporangia: yellow to dark brown or reddish black at maturity; paraphyses absent, maturity: summer to fall.
Habitat: cracks and ledges on cliffs, on a variety of noncalcareous substrates.
Distribution: western North America: British Columbia to northern Mexico, at higher altitudes.
Hardy to -30°C, USDA Zone 4.
A combination of characters is required to be sure of P. hesperium: small, herbaceous, non-leathery fronds, marginal or medial sori under 3 mm, no paraphyses.
Polypodium prolongilobum Clute
Polypodium vulgare Linnaeus subsp. columbianum (Gilbert) Hultén
Polypodium vulgare var. columbianum Gilbert
Polypodium vulgare var. hesperium (Maxon) A. Nelson & J. F. Macbride
with other species in the Western North America Group