Rhizome short to c. 15 cm long, erect, narrow and very woody. Stipes stramineous or brownish, of sterile fronds 6-60 cm long, of fertile fronds 10-70 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, oval, or triangular, aerophores present on stipe and rachis, elongate, horn-like, with blunt apex; rachises glabrous to hairy to sometimes densely hairy. Fronds not covered with an amorphous gelatinous mucilage layer when dry, dorsal side of rachis flattened, semiterete or grooved, not winged (or winged on ridges), rachis 1-4 mm wide in the middle part. Sterile lamina herbaceous, not glaucous, pinnate except the pinnatifid or pinnatilobed apex, widest medially, 15-100 by 6-40 cm, index (1.8-)2.3-2.8(-4.1); pinnae 20-50 pairs, widest near the base or below the middle, veins of pinnae simple or up to half 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, slightly deflexed or not, gradually or slightly shortened, some pinnae vestigial on stipe sided by aerophores; middle pinnae 3-20 cm long, 0.6-2 cm wide in the middle, sessile, base truncate or rounded; 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, 3-7 cm long. Fertile fronds usually longer than the sterile ones, dorsal side of rachis flattened, semiterete, or grooved, not or sometimes winged on the ridges (slightly, also along the corner line of the stipe); lamina pinnate throughout, pin-nae shortly stalked or nearly sessile, 20-70 by 4-20 cm wide; pinnae glabrous, 16-40 pairs, margin erose; lowermost pinnae gradually shortened or some pairs aerophore-like vestiges on stipe together with aerophores, 2-4(-5) cm apart; middle pinnae (3-) 4.5-13(-21) cm long, 2-4 mm wide, base sessile, slightly cordate, or shortly stalked; apex pinnatifid, acuminate or caudate or terminated by a pinna conform to the lateral ones and often beaded at the base. Paraphyses few, mostly lost, dark brown or brown. Spores yellow to brown, not obviously tuberculate.
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Stipes 6-60 cm on sterile fronds, 10-70 cm on fertile fronds, distally tetragonal, terete, ovate, or triangular 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, 15-100 × 6-40 cm, not glaucous, apically with a pinnatilobed segment or a pinnalike segment; rachises abaxially flattened, semiterete, or grooved; pinnae 20-50 pairs; proximal pinnae sessile to shortly stalked, base truncate or rounded, subdeflexed or not, gradually abbreviated or slightly shorter, sometimes becoming vestigial on stipe; middle pinnae sessile, base truncate or rounded; veins simple or sometimes 1-forked. Fertile lamina pinnate, 20-70 × 4-20 cm; rachises abaxially flattened, semiterete, or grooved, sometimes winged; pinnae 16-40 pairs, sessile or shortly stalked; proximal pinnae gradually abbreviated or some pairs aerophore-like or vestigial. Paraphyses few, shed early, brown or dark brown. Spores yellow to brown, not obviously tuberculate.
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