Description from Flora of China
Adiantum roborowskii Maximowicz var. robustum Christ.
Plants epilithic, 16-35 cm tall. Rhizomes shortly creeping or ascending, scales dense, castaneous-black, glossy, narrowly lanceolate, margins entire. Fronds clustered or closely spaced; stipe castaneous, glossy, 5-22 cm, base densely covered with same scales as rhizome, distally glabrous; lamina 3-pinnate, lanceolate-triangular in outline, 4-22 × 4-8 cm, base cuneate, apex acuminate; pinnae 4-7 each side, stalk 5-10 mm; costae and stalks similar to stipe, glabrous, obliquely ascending; basal pinnae slightly larger, 2-pinnate below middle, narrowly ovate, 2.5-4 × ca. 2 cm, and with 2 pairs of pinnules; distal pinnae 1-pinnate; pinnules 3 or 4 pairs per pinna, alternate, obliquely ascending; stalk ca. 1 mm, slender; blade narrowly flabellate or obovate, 5-14 × 4-10 mm, progressively slightly smaller distally, papery, yellow-green or dark brown-green, both surfaces glabrous, base narrowly cuneate, bilateral sides symmetrical, undulate-crenate, outer and inner margins entire; sterile pinnules with upper margins distinctly bluntly triangular serrate, upper margin of fertile pinnules with wide and deep sinus at middle. Veins multidichotomously forked, reaching margins, visible on both surfaces. Sori 1(or 2) per pinnule, in sinus of upper margin; false indusia dark brown, orbicular or orbicular-reniform, subleathery, upper margins deeply sinuate, entire, persistent. Perispore granular.
Reviewer Ralf Knapp questions the occurrence of Adiantum erythrochlamys in Taiwan.
The authors have not seen material of Adiantum erythrochlamys var. hunanense C. M. Zhang (in W. T. Wang et al., Keys Vasc. Pl. Wuling Mts. 563. 1995), described from Shimen, Hunan, and so cannot confirm its status.
● On rocks or in rock crevices in forests by streamsides; 600-3500 m. Guizhou, Henan, Hubei, Sichuan, ?Taiwan, Xizang.