Rhizome short-creeping, c. 2 mm ø; scales reddish brown, narrowly triangular, to 2.5 mm long, to c. 10-seriate at base, with a short uniseriate apex. Leaves close; petioles stramineous, triangular, especially the abaxial keel pronounced, acute, (5-)15-30 cm long, mostly somewhat shorter than the lamina. Lamina oblong, mostly olivaceous or dark green when dry, thinly herbaceous, 10-35 cm long, bipinnate (once pinnate in juvenile but nearly always sterile plants), with 3-9 pinnae to a side and a conform terminal one. Primary rachis similar to the petiole. Pinnae obliquely ascending, mostly not close, sessile, 7 by 1 to 15 by 2 cm, acuminate; secondary rachises abaxially sharply carinate virtually to the base; upper pinnae little or not shortened. Pinnules c. 20-45 to a side, mostly rather close, often subcontiguous, spreading, slightly ascending, or occasionally somewhat falcately decurved, semi-ovate in outline, subsessile, 5-14 mm long, 2.5-4 mm wide, 2-3.5 times as long as wide; lower edge straight or +-concave, upper edge especially towards the apex convex, a distinct outer edge scarcely developed. Pinnules deeply incised from the upper margin into 4-6 major segments, the larger ones nearly always forked, the apical one often protracted and pinnatilobate; ultimate lobes linear, parallel-sided to near the slightly broadened apex if fertile, rounded or subacute if sterile, the outer ones progressively shorter and more oblique, rounded or erose at apex, 1/4-3/4 mm wide, the wing joining them 1/2-(at the base of the pinnule) 1 mm wide. Upper pinnules gradually and strongly reduced, confluent into a narrow, pinnatifid pinna-apex. Veins single or less often paired in the ultimate lobes, immersed, evident. Sori uni-or less often binerval; indusium pale, entire or subentire, 0.4-1 mm long, 0.2 mm wide, if short with flat or convex, if longer with concave base, reaching the margin to falling short of it by almost its width. Spores pale brown, trilete, smooth, c. 20 μ.
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