Polypodium Western North America Group

Note particularly: the taste, size, and color of the rhizome for all species, the size of the sorus and netted venation in P. scouleri, the presence of paraphyses (translucent, glandular branching structures within the sorus; hand lens required) in P. amorphum, the downy rachis above of P. californicum and P. glycyrrhiza. Frond size is generally a poor identifier, but at the extremities, P. hesperium is always small, P. glycyrrhiza is robust.

Species Rhizome Form Blade Height To Blade Texture Blade Indument Sori Sori Position Sporangia Distribution
amorphum creeping, branching, whitish waxy, rather thick, acrid-tasting, to 6 mm diameter 50 cm somewhat leathery, mid-green, dull in shade rachis glabrous above, sparsely scaly below, scales lanceolate-ovate oval when young (and closer to the rachis), more round later, discrete, less than 3 mm diameter, sunken into the lamina, bulging on the top surface midway between margin and midrib, on the upper half of the blade early green, later yellow, then rusty brown; paraphyses present British Columbia to Oregon, disjunct in Wyoming, Colorado
californicum creeping, branching, dull, not whitish waxy, moderately stout, to 10 mm diameter, acrid to sweet (but not licorice) flavored 70 cm leathery to herbaceous rachis downy above, a diagnostic feature, a few scattered scales on the rachis below oval when immature, round later, discrete, less than 3 mm diam midway between margin and midrib to slightly nearer the midrib; on all but the lowest pinnae of fertile fronds yellow to brown at maturity; paraphyses absent California and Baja California
glycyrrhiza creeping, branching, not whitish waxy, slender to moderately stout, to 6 mm diameter, sweet, licorice flavored 75 cm herbaceous rachis downy above, a diagnostic feature, also on the pinna midrib (costa) round or sometimes oval when immature, discrete, less than 3 mm diam midway between margin and midrib to nearly marginal; on all but the lowest pinnae of fertile fronds yellow to brown at maturity; paraphyses absent Kamchatka, north to the Aleutians, south to California, disjunct in Idaho
hesperium creeping, branching, slender, whitish waxy sometimes, about 5 mm diameter, acrid to sweet flavored 25 cm herbaceous, ligt to yellowish-green glabrous above, sometimes a few scales below 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 yellow to dark brown or reddish black at maturity; paraphyses absent western North America: British Columbia to northern Mexico, at higher altitudes
scouleri creeping, branching, whitish waxy, stout, to 12 mm diameter, bland to slightly sweet-tasting 60 cm leathery, stiff, glossy, dark green rachis, glabrous above, sparsely scaly to glabrescent below round when immature, usually more than 3 mm diameter crowded against midrib, sometimes merging when mature yellow to brown at maturity; paraphyses absent British Columbia to Baja California

Characters listed were chosen for their value in distinguishing between species.

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