日本双盖蕨 ri ben shuang gai jue

Allantodia nipponica (Tagawa) Ching; Athyrium nipponicola Ohwi.

Plants medium-sized to large. Rhizome creeping, ca. 1 cm in diam., apex with loose scales; scales black-brown, narrowly lanceolate, ca. 5 mm, thickly membranous, margin toothed; fronds approximate. Fertile frond 80-140 cm; stipe brown at base, upward stramineous, 40-60 cm, ca. 8 mm in diam. at base, with dense scales similar to those on rhizome, upward glabrous, shallowly grooved adaxially; lamina 2-pinnate with pinnules pinnatipartite to pinnatisect, 60-80 × ca. 50 cm at base, apex acuminate; pinnae 8-10 pairs, alternate, ascending, lower pinnae ca. 10 cm apart, with stalk ca. 3 cm; basal pinnae largest, broadly lanceolate, ca. 40 × 10 cm, narrowed to base, base cuneate, apex acuminate; pinnules 10-12 pairs, alternate, spreading, ca. 2 cm apart, shortly stalked, lanceolate, ca. 7 × 2 cm, base cuneate, pinnatifid, apex acuminate; pinnule lobes ca. 8 pairs, ascending, oblong, ca. 6 × 5 mm, slightly narrowed to obtuse apex, margin minutely serrate, lateral margin entire; veins pinnate, not prominent, veinlets ca. 5 pairs per pinnule lobe, simple or forked, ascending. Lamina gray-green or gray-brown when dry, herbaceous, glabrous on both surfaces; rachis stramineous, glabrous, shallowly grooved adaxially, costae occasionally with linear brown scales. Sori linear, 2-6 mm, 2-4 pairs per pinnule lobe, borne from costule to near pinnule margin, single or double on basal acroscopic veinlet; indusia light gray, linear, membranous, persistent. Spores reniform, perispore prominent, rugate.

● Shaded places in valley forests, beside streamlets; ca. 800 m. Zhejiang.