Adiantum aleuticum (Ruprecht) C. A. Paris; A. boreale C. Presl; A. pedatum var. aleuticum Ruprecht; A. pedatum var. glaucinum C. Christensen (1927), not Christ (1898); A. pedatum var. kamtschaticum Ruprecht.

Plants terrestrial, 40-60 cm tall. Rhizomes erect or decumbent, scales dark brown, broadly lanceolate, margins entire. Fronds clustered or approximate; stipe castaneous or brown, 20-40 cm, covered with same scales as rhizome, distally glabrous; lamina pedately dichotomous, broadly flabellate in outline, up to 30 × 40 cm; pinnae 4-6 per branch, 1-imparipinnate, linear-lanceolate in outline; rachises and stalks castaneous-red, glabrous; inner pinnae up to 28 × 2.5-3.5 cm, outer pinnae slightly shorter; pinnules 20-30 pairs per pinna, alternate, obliquely spreading; stalk 1-2.5 cm; basal pinnules slightly smaller, flabellate or semi-orbicular, with longer stalks; middle pinnules dimidiate, narrowly triangular, ca. 2 × 0.6 cm, herbaceous, green, both surfaces glabrous, base asymmetrical, cuneate, inner and lower margins straight and entire, apex undulate or with blunt teeth, upper margin divided to halfway, apex obtuse; segments ± square, entire or depressed at middle or undulate-crenate; distal pinnules similar but gradually smaller toward apices, terminal pinnules flabellate, divided at middle, bilateral sides lobed, equal in size or slightly larger than middle pinnules; veins multidichotomously forked, reaching margin, visible on both surfaces. Sori 4-6 per pinnule, horizontally attached in shallow sinuses; false indusia grayish green or dark brown, orbicular or reniform, membranous, entire, persistent. Perispore granular.

The whole plant is used in traditional Chinese medicine.

The authors have not seen material of Adiantum pedatum var. grandifolium (Ching) Ching (Acta Phytotax. Sin. 6: 324. 1957; A. grandifolium Ching, Bull. Fan Mem. Inst. Biol., n.s., 1: 269. 1949), described from Yunnan, and so cannot confirm its status.

Near streamsides in forests; 300-3500 m. Gansu, Hebei, Heilongjiang, Henan, Jilin, Liaoning, Qinghai, Shaanxi, Shanxi, Sichuan, Xizang, Yunnan [Bhutan, NE India, Japan, Korea, Nepal; North America].