Stems creeping, 5--8 mm diam., densely scaly; scales tan to brownish, lanceolate. Leaves monomorphic, evergreen, 40--85 cm. Petiole straw-colored to tan, spaced 0.5--4 cm apart, 15--46 cm × 4--6 mm, base scaly; scales lanceolate. Blade deltate-pentagonal, 2--3-pinnate, 24--40 cm, broadest at base, abruptly tapering distally, apex pinnate, ultimately pinnatifid, as long as or longer than rest of blade. Pinnae 3--5 pairs, 1-pinnate, proximal pair basally 2-pinnate, 8--18 × 2--4 cm (excluding expanded base of proximal pinnae). Basal pinnules of proximal pair of pinnae elongate and pinnalike; basiscopic pinnule to 10 cm, acroscopic pinnule 1/3--1/2 length of basiscopic. Ultimate segments undivided to pinnatifid, finely spiny along margins and at tip. Sori with indusia 0.5--1 mm diam., indusia with deep sinus and often overlapping lobes, glabrous.

Terrestrial along stream banks in woods; 0 m; introduced; S.C.; Asia in Japan, China.

Arachniodes simplicior was introduced and naturalized in South Carolina and is known from a single population there (J. E. Gordon 1981). It was still locally common in April 1990 and apparently poses no threat to the native flora.