Rhizome long-scandent, dark castaneous, 1-2 mm ø; scales when mature dark brown, narrowly triangular or lanceolate, to 2.5 by 0.75 mm, up to c. 15-seriate at the base, the uniseriate apex very short. Leaves remote, 1-5 cm apart, not rarely issuing almost at right angles; petioles abaxially bi-angular, mostly brown and pale-angled but sometimes quite stramineous except at the base, 2-10 cm long (exceptionally longer), much shorter than the lamina, at the most half as long. Lamina linear, 15-50 cm long (rarely shorter but fertile), 2-4.5 cm wide, 5-15 times as long as wide, in juvenile plants usually broadest just below the apex, in full-grown ones narrowed to both ends, simply pinnate, with c. 20-60 pinnules to a side; rachis pale brown, stramineous-margined, or stramineous throughout, at the base sharply quadrangular with flat or slightly convex faces, the pinnules in the basal part inserted below the adaxial face, upward sulcate. Pinnules herbaceous or chartaceous, dark green or blackish when dry, sometimes described as glossy, less than their width apart to slightly overlapping, spreading, the lower ones not rarely deflexed and the upper ones somewhat ascending, dimidiate-ligulate or trapezoidal, broadly rounded or narrowed-rounded at the apex; larger pinnules 10 by 5 to 22 by 9 mm, 2-2.5 times as long as wide, entire; sterile or incompletely fertile pinnules crenate. Lower pinnules gradually reduced but few or none so strongly as to be auriculiform; upper pinnules not reduced in juvenile plants, increasingly so in older ones, in the largest leaves several very small ones connected with the small lanceolate terminal segment; small leaves with a large, free, very obtuse, transversely elongate, asymmetrically lance-shaped or flabellate or broadly lanceolate terminal pinnule, with all intermediates between the two extremes possible. Veins immersed, +-evident, once or twice forked, free, 0.75-1.25 mm apart. Sori continuous, occupying all vein-ends, interrupted only in incompletely fertile pinnules; indusium 0.3-0.5 mm wide, pale, subentire, not reaching the margin by 0.5-1 times its width. Spores yellowish brown, trilete, almost smooth, c. 20 μ.
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