Rhizome short to c. 15 cm long, erect, suberect to curved, or decumbent, narrow and very woody or thick with many stipe bases. Stipes stramineous or brownish, of sterile fronds 3-55 cm long, of fertile fronds 5-75 cm long, base strongly enlarged, 5-15 mm wide in the middle, in cross section one U-shaped vascular bundle, upper part of stipe tetragonal, terete, or oval, aerophores present on stipe and rachis, elongate, horn-like with blunt apex; rachises glabrous to hairy or sometimes densely hairy. Fronds not covered with an amorphous gelatinous mucilage layer when dry, dorsal side of rachis semiterete to flattened or grooved, not winged, rachis 0.5-4 mm wide in the middle part. Sterile lamina firm herbaceous or subcoriaceous, glaucous beneath, pinnate except the pinnatifid or pinnatilobed apex, widest medially or a little higher, 7-110 by 2-30 cm, index (1.8-)2.8-3.8(-4.6); pinnae 13-43 pairs, widest below or about the middle to near the base, veins of pinnae as many simple as forked, distinct on both surfaces, stomata scattered on the lower epidermis, margin serrulate, most pinnae except the uppermost with equilateral base, truncate or rounded; lowermost pinnae sessile to shortly stalked, not or slightly deflexed, abruptly shortened or not, some pinnae vestigial on stipe sided by aerophores; middle pinnae 1-15.5 cm long, 0.6-1.8 cm wide in the middle, sessile, base truncate or rounded (at dry stage); apex of lamina pinnatifid, terminated by a pinnatilobed segment or by a pinna conform to lateral ones, base connected with 1 or 2 shorter lateral pinnae or rarely with 1-3 irregular auricles, 1-10 cm long. Fertile fronds usually longer than the sterile ones, dorsal side of rachis semiterete, flattened, or grooved, not winged, rachis 0.5-4 mm wide in the middle part; lamina pinnate throughout, pinnae shortly stalked or nearly sessile, 11-77 by 4-24 cm; pinnae glabrous, 13-43 pairs, margin subentire to erose; lowermost pinnae gradually shortened or some pairs aerophore-like vestiges on stipe together with aerophores, 2-4 cm apart; middle pinnae 2-14 cm long, by 2-4.5 mm wide, base shortly stalked, sessile, or slightly cordate; apex pinnatifid, acuminate or caudate. Paraphyses few, mostly lost, dark brown or yellow. Spores yellow to brown, not obviously tuberculate.
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Stipes 3-55(-60) cm on sterile fronds, 5-75 cm on fertile fronds, distally tetragonal, orbicular, or ovate in cross section; vascular bundle U-shaped; stipes and rachises glabrous to hairy, sometimes densely hairy; aerophores elongate and hornlike with blunt apex. Sterile lamina pinnate, 7-110 × 2-30 cm, glaucous abaxially, apically with a pinnatilobed segment or a pinnalike segment; rachises abaxially semiterete to flattened, or grooved; pinnae 13-43 pairs; proximal pinnae sessile to shortly stalked, base truncate or rounded, not deflexed to subdeflexed, abruptly abbreviated or not, sometimes becoming vestigial on stipe; middle pinnae sessile, base truncate or rounded; veins as many simple as forked. Fertile lamina pinnate, 11-77 × 4-24 cm; rachises abaxially semiterete, flattened, or grooved; pinnae 13-43 pairs, shortly stalked or sessile; proximal pinnae gradually abbreviated or some pairs becoming aerophore-like vestiges. Paraphyses few, shed early, dark brown or yellow. Spores yellow to brown, not obviously tuberculate.
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