Rhizome long-scandent, 1.5-3 mm ø; scales golden brown, narrowly triangular, to 3 by 0.5 mm, to c. 10-seriate at base, with a short uniseriate apex. Leaves usually 2.5 cm or more apart, rarely closer; petioles issuing almost at right angles from the rhizome, olivaceous-to dark brown, often with elongate, paler protuberances, abaxially terete, adaxially at least above flattened to sul-cate, 10-40 cm long, about equaling to much longer than the lamina. Lamina oblong, 20-50 cm long, bipinnate, with 1-7 pairs of usually sub-opposite pinnae and a conform terminal one; primary rachis abaxially terete or upward obtusely bi-angular, adaxially broadly and shallowly sulcate, with obtuse lateral ridges. Pinnae not close, often 6-8 cm apart, ascending, linear, sessile, 10-25 cm long, 10-20 mm wide, gradually taper-ing from the lower third or the middle upward; secondary rachises brown, abaxially sharply bi-angular except for a short terete basal portion, the angles often paler, the face between them flat or concave. Upper pinnae of plurijugate leaves slightly shortened. Pinnules herbaceous to rigidly coriaceous, mostly dark olivaceous to blackish when dry, usually spreading, c. 25-45 to a side, their width apart or less but not contiguous, subtrapeziform, obliquely ovate, or 1/4-elliptic, the larger ones 7 by 3 to 12 by 6 mm, mostly twice (to 2.5 times) as long as wide, narrowed (sometimes very little) from base to apex; margins pale-sclerotic, especially in rigid pinnules; lower margin straight or distally convex, upper margin distally gradually convex, a distinct outer margin usually not developed. Upper margin of sterile pinnules (bi)crenate to dentate, of fertile pinnules crenate with incisions to 1 mm deep, less in rigid pinnules, the lobes subtruncate. Veins immersed and evident in herbaceous, ± elevated on both sides in rigid pinnules, simple or once, rarely twice, forked, free, connivent, or with one anasto-mosis between Upper and lower margin, the anastomoses irregular, often involving only part of the veins and mostly not found in all pinnules. Upper pinnules very gradually and strongly re-duced, some denticuliform ones confluent into a narrow, lobed pinna-apex. Sori 1-4 per pinnule, 1 per lobe, on the outer lobes; larger pinnules only partly soriferous, the inner part of the upper margin sterile; very often only the outermost sorus present, on 2-6 veins, to 5 mm long; inner sori shorter. Receptacle straight or with convex ends; indusium mostly rigid, brownish, subentire to erose, narrowed at the adnate ends, 1/2-3/4 mm wide, not quite reaching the margin, reflexed or not at maturity. Spores dark brown, trilete, slightly pustulate, c. 25 μ.
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