Caudex short, erect; stipe of sterile frond to 30 cm long, of fertile to at least 45 cm; basal scales 10 mm long, narrow; sterile frond tripartite, broadly deltoid-pentagonal in outline; terminal lamina deltoid, deeply multi-lobed, the lobes all entire, acute to acuminate, the lower ones slightly reduced or in the largest fronds elongate and deeply lobed; pinnae opposite or nearly so, to 16 cm long, short-stalked, deeply lobed, the basal basiscopic lobe to 9 cm long, asymmetric, wider and more deeply lobed on its basiscopic side, a bud present at the base of each pinna; veins forming areoles along costae of lobes of apical lamina and of pinnae, sometimes with additional areoles below sinuses between lobes; lower surface of costae variously hairy, hairs on some Sumatran specimens more than 1 mm long, usually shorter or lacking; upper surface always densely short-hairy on costae, between veins scattered thick hairs variously abundant; fertile frond shaped as sterile but all parts narrow; venation of very narrow areoles; sporangia abundant all along veins; spores with very thin translucent wing; n = 40 (Walker).
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