锯齿双盖蕨 ju chi shuang gai jue

Diplazium saposhanense Ching.

Rhizome erect, black, 4-5 cm tall, robust, woody, stiff, with dense stiff, long, thick roots, apex densely scaly; scales black, lanceolate, 2-3 × ca. 0.4 mm at base, thick, small serrate at margin; fronds caespitose. Fertile frond ca. 75 cm; stipe black-brown at base, upward stramineous or green-stramineous, 30-45 cm, 2.5-3 cm in diam., stiff, base with sparse scales, upward glabrous, shallowly grooved adaxially; rachis stramineous, glabrous; lamina 1-imparipinnate, elliptic, 30-40 × 10-20 cm; lateral pinnae 1-5 pairs, equal in size, lower pinnae opposite or subopposite, with stalk 0.3-1 cm; upper pinnae mostly alternate, subsessile, oblique, elliptic-lanceolate, 11-18 × 2.2-4 cm, base broadly cuneate, symmetrical or asymmetrical, base of apical pinna usually narrowed, pinna margin shallowly serrate or shallowly repand throughout, incurved when dry, gradually narrowed to long acuminate at apex, slightly subfalcate; costae raised, rounded, shallowly grooved on adaxial side; veinlets prominent on both surfaces or visible on adaxial side, oblique, 3 or 4 per veinlet group, thin, reaching margin of lamina. Lamina thinly papery when dry, green or brown-green. Sori long or shortly linear, variable in length, oblique, from costa to pinna margin, on 2 or 3 veinlets per veinlet group, sori on acroscopic veinlet longest, all double, other sori short, single, not reaching vein endings.

Tropical rain forests, beside streamlets; 100-900 m. Guangxi, Hainan, Yunnan [Vietnam (Shaba)].

The fertile fronds of Diplazium serratifolium sometimes only have 3 pinnae, so attention to this is needed for proper identification.