62. Asplenium nesii Christ, Nuovo Giorn. Bot. Ital., n.s.,. 4: 90. 1897.
西北铁角蕨 xi bei tie jiao jue
Asplenium barkamense Ching; A. tianshanense Ching.
Plants (2-)6-12(-25) cm tall. Rhizome erect, short, apex scaly; scales dark brown to black, narrowly triangular, 2.5-3 mm, entire. Fronds caespitose; stipe 2.5-8(-10) cm, basal part semi-shiny, castaneous or dark brown to black, toward rachis green or stramineous, sparsely covered with small, black, hairlike scales, adaxially sulcate but compressed when dry; lamina lanceolate, 4-6(-16) × 1-2(-5) cm, reduced at base, 2- or 3-pinnatifid; pinnae 7-9(-15) pairs, alternate or subopposite, shortly stalked, middle pinnae largest, elliptic, 5-15(-25) × 3-8(-15) mm, base nearly symmetrical to asymmetrical, truncate to cuneate, 1- or 2-pinnatifid in large plants, apex acute and pinnatifid, without gemma; pinnules or segments 3-5(-7) pairs, alternate, basal acroscopic pinnule largest, oblong to linear, 4-6 × 1-2(-4) mm, apex obtuse, base cuneate, decurrent and adnate to costa, margin serrate-dentate, teeth often long, obtuse to subacute; other pinnules or segments smaller, many adnate to costa. Veins obscure, 2-forked or simple, not reaching margin. Fronds herbaceous to subleathery, gray-green; rachis green or stramineous when dry, rarely brown at base abaxially, adaxially sulcate, with small, dark brown, hairlike scales. Sori 2-4 per pinnule, basal to submedian on subtending vein and thus close to costa or costule, confluent at maturity, linear, 1-1.5 mm; indusia grayish brown to whitish, linear-elliptic, membranous, entire, opening toward costa or costules. Spores with lophate (costate) perispore. Plants tetraploid: 2n = 144.
Crevices of relatively dry rocks; 1000-4000 m. Gansu, Hebei, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shanxi, Sichuan, Xinjiang, Xizang, Yunnan [Afghanistan, N India, Nepal, N Pakistan].
Asplenium nesii is similar to larger forms of A. exiguum, but its pinna apices are without gemmae, the stipe is green toward the rachis, and the rachis itself is usually entirely green. Asplenium barkamense is a luxurious form from Sichuan, but locally not rare in Xizang. Type specimens of A. ×mainlingense Ching & S. K. Wu (Fl. Xizang 1: 184. 1983, pro sp.) are hybrids with aborted spores. They probably represent a cross between A. nesii and A. varians or A. tenuicaule, which all occur in the area close to the type locality near Mainling, Xizang.