Stems forming a stout caudex covered with petiole bases, suberect; scales light brown, many, lanceolate-attenuate. Leaves monomorphic, evergreen, numerous in vaselike cluster, 40-170 cm. Petiole straw-colored, sometimes reddish at base; base thickened, with densely set orange scales. Blade pale green, elliptic-lanceolate, 25-100 cm, scaly-glandular upon emergence but soon glabrate. Pinnae not articulate to rachis, in 8-24 pairs, narrowly deltate to lanceolate, pinnatifid; proximal to middle pinnae 12-42 × 2.5-8 cm. Veins anastomosing to form single row of areoles, then free to margin. Sori short and broad, mostly curved and confined to costular areoles, deeply sunken into blades. Indusia cartilaginous and vaulted; cells thickened, retaining configuration after dehiscence of sporangia. 2 n = 68.
Rhizomes stout, short-creeping to suberect; fronds mostly erect to ascending; stipes (18-)30-60(-72) cm long, abundantly scaly at base, the scales brownish to orange-brown; blades pinnatepinnatifid, 25-100 cm long, broadest at or just below the middle, distal pinnae subcordate at the base; rachises sparsely scaly to usually glabrescent; pinnae (8-)10-24 pairs, the proximal pair distant from the rest, the lower and middle ones mostly 15-25 x 3.5-9 cm, pinnatifid, asymmetric at base by the reduction of the basalmost basiscopic lobe(s); pinna lobes broadly attached at base, narrowed gradually distally or with margins parallel for some distance to the acute to obtuse apex, frequently with margins of proximal pinnae crenate to deeply incised, the lobes spinulose along the margins; indument abaxially of sparse fibrillose scales less than 0.5 mm long on costules, veins, and leaf tissue, also of sparse, stramineous to whitish, linear-lanceolate scales to ca. 2 mm along costae, these often deciduous, laminae abaxially often with yellowish resinous glands and short-stipitate glands; sori usually confined to costular areoles, short-linear, (1-)2-5mm long, mostly 2-4 times as long as broad, straight or curved, deeply sunken into the blade tissue; indusia cartilaginous and vaulted, persisting and retaining form after sporangial dehiscence; spores 64 per sporangium; 2n=68 (Calif).
Terrestrial, along streambanks and springs; 400-2100 m. Canada (British Columbia, especially Vancouver Is),USA (Ariz, Calif, Nev, Ore, Wash); Mexico.
|Giant chain fern|