Leathery Polypody

The distinctive Polypodium scouleri has occasionally been assigned to the genus Goniophlebium because of its anastomosing venation and conspicuous areoles. Its venation pattern can be quite variable, however, and cannot be used as the sole feature distinguishing P . scouleri from P . californicum . Combining venation characteristics with others provided in the key distinguishes it clearly from its congeners in Polypodium . Some evidence suggests that P . scouleri hybridizes with P . californicum (S. A. Whitmore, unpubl.). I. Manton (1951) reported diploid and triploid cytotypes for P . scouleri , and variation in spore size suggests that the species may also include tetraploid populations.

Stems conspicuously whitish pruinose, stout, 3--12 mm diam., bland to slightly sweet-tasting; scales concolored to weakly bicolored, uniformly dark brown or with pale margins and base, lanceolate, symmetric, margins denticulate. Leaves to 85 cm. Petiole stout, to 3 mm diam. Blade ovate-lanceolate, pinnatifid, usually widest just above base, to 27 cm wide, stiff and leathery; rachis sparsely scaly to glabrescent abaxially, glabrous adaxially; scales bicolored, ovate-lanceolate, much more than 6 cells wide. Segments oblong to linear, usually more than 12 mm wide; margins entire to crenulate; apex rounded to rarely broadly acute; midrib glabrous adaxially. Venation anastomosing, usually forming 1 row of areoles. Sori crowded against midrib, usually more than 3 mm diam., circular when immature. Sporangiasters absent. Spores usually less than 52 µm, rugose, surface projections less than 3 µm tall. 2 n = 74, 111.

B.C.; Calif., Oreg., Wash.; Mexico in Baja California.

Sporulating late fall--spring. Cracks and ledges on cliffs, occasionally epiphytic; on a variety of substrates but preferring volcanic substrates in warmer, drier climates, rarely far from ocean; 0--500m.

Polypodium scouleri occurs from British Columbia south through Washington State, Oregon, California and Baja California (Guadalupe Island). Within the core range of California the species is found in a variety of sub-regions including the North Coast, Outer North Coast Ranges, Central Coast, San Francisco Bay Area.

Polypodium scouleri is a species of fern known by the common names leathery polypody, Scouler's polypody, coast polypody and leather-leaf fern. It is native to coastal western North America from British Columbia to Guadalupe Island off Baja California. It is a plant of the coastline, growing in cracks on coastal bluffs, in oceanside forests, beach dunes, and similar habitat. It is often affected by heavy fogs and sea spray. This polypody anchors with a waxy, scaly rhizome. It produces triangular or oblong leaves up to 85 centimeters in maximum length and 8 cm width. Each leaf is made up of many round-tipped linear or oblong segments which are usually stiff and leathery in texture and edged with shallow, rounded teeth. The underside of each leaf segment is crowded with rounded sori each up to half a centimeter wide. The sori contain the spores.