掌叶铁线蕨 zhang ye tie xian jue

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.

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].

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.