甘肃铁角蕨 gan su tie jiao jue

Asplenium fimbriatum Kunze var. leptophyllum Zenker ex Kunze; A. propinquum Ching; A. sarelii Hooker ["saulii"] var. latius Christ, p.p.

Plants 5-15(-25) cm tall. Rhizome erect, short, apex scaly; scales dark brown, narrowly triangular, 2-3.5 mm, fimbriate at base or entire. Fronds caespitose; stipe semiterete, 2-8(-10) cm, adaxially green and sulcate, abaxially shiny castaneous, brown color occasionally extending into rachis, with small dark brown, fimbriate scales and uniseriate hairs, subglabrous when old; lamina triangular-ovate, (2-)5-12(-15) × 1-3(-6) cm, apex acute-acuminate, 2- or 3-pinnate; pinnae 8-12 pairs, alternate or basal ones opposite, stalks 1-2 mm, lower pinnae usually somewhat reduced, middle pinnae triangular-ovate, 8-17(-25) × 7-12 mm, base asymmetrical, acroscopically truncate, basiscopic side cuneate, 1- or 2-pinnate, apex obtuse; pinnules 2-4 pairs, alternate, anadromous, basal acroscopic pinnule largest and most divided, broadly ovate, 6-8 × 4-6 mm, base broadly cuneate, shortly stalked, pinnatifid or pinnate, apex obtuse; other pinnules oval to cuneiform, 3 or 4 pairs, reduced toward pinna apex, apical margin serrate and with long, sharp teeth. Costa obvious but veins obscure, veins anadromously branching, often with terminal submarginal hydathode. Fronds thinly herbaceous, when dry grass-green; rachis same color as stipe and sulcate adaxially, abaxially often shiny castaneous at base, becoming green toward apex; lamina with 3- or 4-celled uniseriate gland-tipped hairs, average guard cell length 46-52 µm. Sori 1-3 per pinnule, submedian to median on subtending vein, shortly linear, 1-3 mm; indusia membranous, repand to entire, opening toward costule or costa. Spores with reticulate perispore, average exospore length 33-37 µm.

On rocks in forests; 1100-2000 m. Hebei, Hubei, Shaanxi, Shanxi, Sichuan, Yunnan [S India].

Asplenium kansuense is a putative autotetraploid, which probably originated via chromosome doubling in A. tenuicaule var. tenuicaule. Its general morphology and perispore are very similar to those of that taxon, but its spore size indicates that it is probably tetraploid. No chromosome counts are available. In China, A. kansuense was often misidentified as A. varians or as A. sarelii s.l. Large tripinnate plants resemble tetraploid A. anogrammoides with which they share half of their genome.

The S Indian (Nilgiri) plants belonging to this species (Asplenium fimbriatum var. leptophyllum) occur at higher elevations, are smaller than the Chinese plants, and are similar to both A. varians and A. semivarians. Several chromosome reports of S Indian "tetraploid Asplenium varians" may refer to this species. Large specimens of African A. fimbriatum Kunze are closely similar, also in perispore characters. Hybridization experiments have shown that true A. fimbriatum is an allotetraploid with the same genome composition as A. varians and is thus best considered a variety of the latter (Viane & Reichstein, Pterid. New Millennium, 73-105. 2003): Asplenium varians Wallich ex Hooker & Greville var. fimbriatum (Kunze) Viane stat. nov. (Basionym: Asplenium fimbriatum Kunze, Linnaea 18: 117. 1844; A. varians subsp. fimbriatum (Kunze) Schelpe).