Stems erect or ascending. Leaves arching, 5--18 dm; bulblets absent. Petiole 1/8--1/4 length of leaf, densely scaly; scales red-brown to dark brown or nearly black, gradually diminishing in size distally. Blade linear-lanceolate, 1-pinnate, base slightly narrowed. Pinnae narrowly lanceolate, straight to falcate, not overlapping, pinnae of shade-growing plants in 1 plane, those of sun-growing plants twisted or contorted, 1--15 cm; base ± cuneate, auricles well developed; margins serrulate-spiny with teeth ascending; apex acuminate with subapical teeth same size as apical tooth; microscales ovate-lanceolate to linear-lanceolate, with contorted projections, dense, on abaxial surface only. Indusia ciliate. Spores light yellow. 2 n = 82.
Caudices ca. 3 cm diam.; fronds mostly 60–90 cm long; stipes to ca. 30 cm long, 3–4 mm diam., ca. 1/3–1/2 the blade length; stipe bases and also distal part of stipes with numerous concolorous, brown to red-brown, ovate-lanceolate scales 10–20 x 2– 5 mm, scales entire to sparingly denticulate or rarely ciliate along margins; blades monomorphic, chartaceous, to ca. 60 x 15 cm, broadest at the bases, attenuate at the pinnatifid apices; rachises lacking buds, densely scaly with ovate-lanceolate to narrowly lanceolate, denticulate scales mostly 3–7 x 0.4–0.6 mm; pinnae undivided, very gradually shortened distally, to ca. 50 pairs, mostly 6–10 x 0.8–1 cm (excluding basal auricle), lanceate with a pronounced acroscopic, deltate auricle 3–5 mm long, otherwise serrate-spinulose along both margins, basiscopic bases rounded to cuneate, tips acute and spinulose; indument abaxially along costae and veins of numerous lanceolate scales with contorted bases; sori indusiate, confluent or discrete at maturity, indusia tan to brown with darker brown centers, ca. 1 mm diam., subpersistent; 2n=82 (USA).
Terrestrial in wooded areas; low elevations. Canada, w USA (Alaska to s Calif, east to Mont and n Idaho, disjunct in S Dak); Mexico; naturalized in Europe.
|Common sword fern|