Plagiogyria stenoptera (Hance) Diels

Rhizome short, erect to suberect, thick with many stipe bases. Stipes stramineous, of sterile fronds (3-)4-8(-12) cm long, of fertile fronds (9-)11-22(-28) cm long, base slightly enlarged, 4-8 mm wide in the middle, in cross section one V-shaped vascular bundle, upper part of the stipe tetragonal, aerophores only present on base of stipe; rachises glabrous. Fronds not covered with an amorphous gelatinous mucilage layer when dry, dorsal side of rachis flattened or upwards carinate, with crisped wings on the two ridges or not, rachis 1-2 mm wide in the middle part. Sterile lamina herbaceous, not glaucous, pinnatifid, widest medially, 20-62 by 4-20 cm wide, index (2.6-)3.3-4.3(-5.5); pinnae 25-35 pairs (auricle pinnae excluded), widest near base or medially (in very large forms), veins of pinnae forked above base, distinct on both surfaces, stomata scattered on the lower epidermis, margin serrulate or towards the base becoming entire or nearly so, most pinnae except the uppermost with inequilateral base, adnate to rachis; 3-6(-11) pairs reduced to mere auricles; middle pinnae 2.5-10.5 cm long, 0.7-1.4 cm wide in the middle, acroscopic side of base adnate to the rachis into a wide wing, basiscopic side like the acroscopic side or round (in large fronds); uppermost pinnae adnate, base about equal-sided, basiscopically decurrent into rachis wing; apex of lamina pinnatifid. Fertile fronds usually longer to shorter than the sterile ones, dorsal side of rachis flattened to grooved, sometimes winged on the ridges, rachis 1-2 mm wide in the middle part; lamina pinnate throughout, pinnae nearly sessile or deeply pinnatifid, rachis slightly winged throughout (an abnormal state), (10-)35-55(-75) by 4-8(-12) cm (since pinnae are drooping to one side); pinnae sparsely bearing short glandular hairs (on the inner side), 15-30 pairs (vestigial ones excluded); margin of pinnae entire to subentire; some pairs of lowermost pinnae aerophore-like vestiges on stipe together with aerophores (or sometimes replaced by auricle pinnae like the sterile ones), 2 cm apart; middle pinnae (2.5-)4-6(-12) cm long, 2-3 mm wide, base shortly stalked; apex terminated by a pinna conform to the lateral ones and often beaded at the base. Paraphyses absent. Spores yellow, with reddish tubercles.