大羽双盖蕨 da yu shuang gai jue

Asplenium megaphyllum Baker, J. Bot. 28: 264. 1890; Allantodia megaphylla (Baker) Ching; Diplazium macrophyllum Ching (1929), not Desvaux (1827); D. megaphyllum var. subintegrifolia Tardieu.

Plants medium-sized to large. Rhizome usually robust and erect, brown, ca. 2 cm in diam., woody, occasionally creeping, apex like base of stipe, densely scaly; scales brown, linear-lanceolate to linear-diamond-shaped, ca. 8 mm, membranous, margin black, sparsely toothed, apex curly and filiform; fronds often caespitose, rarely approximate or sparse. Fertile fronds up to 1.5 m; stipe brown at base, upward green-stramineous, 30-80 cm, up to 1 cm in diam., base densely scaly, upward gradually glabrous, broadly grooved adaxially; lamina 1-pinnate, oblong, 50-90 × 25-50 cm, base mostly pinnatipartite, apex deltoid, abruptly shortened and acuminate; lobes with acuminate or long acuminate apex; upward pinnatifid to pinnatilobate, lobes acute or rounded at apex; lateral pinnae 7-9 pairs, alternate, ascending, with stalk ca. 5 mm, base slightly asymmetrical, shallowly cordate, few nearly symmetrical, rounded-cuneate, margin with few sinuses or serrate, apex acuminate; veins prominent, slightly raised on both surfaces, pinnate, ascending, veinlets 4-6 on either side of main veins, ascending, simple, basiscopic 2 or 3 veinlets not reaching pinna margin. Lamina papery, usually dark green when dry, glabrous on both surfaces; rachis stramineous, glabrous, shallowly grooved adaxially; costa abaxially with sparse linear brown scales. Sori linear, 3-6 mm, 3 or 4 pairs per vein group, mostly single or sometimes double, inframedial or medial; indusia gray, linear, membranous, entire. Spores bean-shaped, perispore prominent, few rugate.

Valley forests, beside streamlets, mostly in calcareous areas; 100-1700 m. Chongqing, Guangxi, Guizhou, Sichuan, Taiwan (Hualian, Nantou), Yunnan [E Myanmar, N Vietnam].