西藏双盖蕨 xi zang shuang gai jue

Basionym: Allantodia tibetica Ching & S. K. Wu, Fl. Xizang. 1: 147. 1983.

Plants evergreen, medium-sized to large. Rhizome creeping, black-brown; fronds sparse to caespitose. Fertile fronds up to 1.6 m; stipe black-brown at base, upward brown or pale brown, up to 80 cm, up to 7 mm in diam., sparsely scaly; scales brown, lanceolate, thickly membranous, margin sparsely toothed; lamina 2- or 3-pinnate, deltoid, up to 80 × 60 cm, apex acuminate; pinnae 6-10 pairs, alternate; basal 3 pairs of pinnae oblong, slightly ascending, up to 40 × 20 cm, base slightly narrowed, with stalk ca. 1 cm, pinnate, apex acuminate; middle pinnae ovate-lanceolate, pinnatilobate to pinnatifid, apex acuminate; upper pinnae lanceolate, margin shallowly incised or subentire, base broader, shallowly cordate or broadly crenate, shortly stalked or sessile, ± auriculate; pinnules 8 pairs, lanceolate or narrowly ovate, up to 10 × 2.5 cm, base broader, broadly cuneate or subtruncate, sessile or subsessile, margin shallowly incised or repand, or entire, apex acuminate; lobes of lower pinnae up to ca. 9 pairs, oblong and rounded, or subdeltoid, slightly falcate, entire, acute at apex; veins prominent abaxially, slightly visible adaxially, veinlets simple, few forked, oblique, up to 6 pairs at base of pinnule. Lamina thinly membranous when dry, pale abaxially, dark brown-green adaxially; rachis, costae, and costules abaxially sparsely scaly; scales brown, lanceolate, toothed. Sori linear, subcostular or inframedial, from costule or near costule to 1/2-2/3 of veinlet length, single or double on basal acroscopic veinlets; indusia brown, membranous, lacerate, opening acroscopically when mature. Spores reniform, perispore prominent, few rugate.

● Broad-leaved forests; 900-1900 m. SE Xizang (Mêdog).