Roots proliferous. Stems erect, not branched; scales blackish throughout or rarely with narrow pale margins, narrowly linear, mostly only 8--12 cells wide proximally, 2--3 × 0.5--0.8 mm. Leaves monomorphic. Petiole blackish to greenish, dull, 1--7(--17) cm, 1/5--1/2 length of blade; glabrous with few scales at base. Blade oblong-lanceolate, 2--3-pinnate, (2--)6--12(--18) × 2.7--10 cm, thin, glabrous; basal pinna pairs unreduced to reduced 1/4; apex gradually reduced, not rooting. Rachis blackish, dull, glabrous. Pinnae in (7--)10--15(--20) pairs, oblong, 2-pinnate throughout; medial pinnae (1--)2--3(--6) cm, all ± curved upward; proximal pinnae descending; base cuneate; apex attenuate. Pinnules ± asymmetric, 1--5(--10) × 1--4 mm; margins strongly dentate, cut 1/3--1/2 to axis. Veins free, evident. Sori 1--4(--6) per pinnule, usually on both basiscopic and acroscopic sides. Spores 64 per sporangium. 2 n = 72.
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