Trunk 5-15 m or sometimes more than 20 m, 10-20 cm in diam. or more, densely covered by adventitious roots. Fronds 2-pinnate-pinnatifid; stipes persistent and forming an irregular skirt, lustrous, greenish, purple-black toward base, 30-50 cm, with spines and lustrous brown scales; scales on trunks and stipes dark brown, lustrous, several cells thick, stiff, narrowly lanceolate, apex dark brown, setose, with pale and thin toothed margins, scales falling off leaving sharp prickles at base. Lamina 2-pinnate-pinnatisect, oblong-obovate; middle pinnae oblong, 40-50 × 14-18 cm; pinnules 18-20 pairs, basal pinnules shorter, middle ones lanceolate, 9-12 × 1.2-1.6 cm, base cuneate, sessile or shortly stipitate, apex long acuminate and caudate, pinnatisect; pinnule segments 18-20 pairs, ascending, basal segments shorter, middle ones falcate, up to 7 × 4 mm, margin dentate, apex acute or mucronate; veins pinnate. Lamina papery, green; abaxial side with small membranous pale scales, adaxial side of rachis, costa, and midvein densely hairy. Sori at forks of lateral veinlets; indusia globose, thin, membranous, completely enveloping sori from base when young, irregularly falling off at maturity.