Rhizome long-scandent, dark brown, 1-2 mm ø; scales deciduous, dorsally more persistent, lemon-coloured to light brown, elongate-triangular, to 3.5 by 1 mm, up to c. 20-seriate at base, with a very short uniseriate apex. Leaves 1-4 cm apart; petioles virtually absent to 8 cm long, stramineous with dark base or brown and then often pale-angled, quadrangular, only if very short sometimes subterete, very much shorter than the lamina. Lamina linear, 25-50 cm long, 2.5-4.2 cm wide, moderately to strongly narrowed at base, acuminate, with c. 35-60 pinnules to a side; rachis stramineous, sharply quadrangular, adaxially flat or shallowly sulcate, abaxially usually flat. Pinnules spreading or somewhat ascending, elongate-triangular or less often semi-ovate, herbaceous, medium to dark green when dry, the larger ones 11-22 mm long, 4-6 mm wide, 2-4.5 times as long as wide, narrowed from base to apex, the apex subacute or less often narrowed-rounded or rounded; lower margin straight, outward convex; upper margin approximately straight, regularly dentate if sterile, more irregularly crenate or dentate if fertile, the incisions 0.5-1 mm deep, not reaching down to the middle except sometimes near the apex; teeth narrowed from base to apex, acute if sterile, obtuse and erose to acute and often very irregularly erose if fertile, the middle more protruding. Basal pinnules reduced and remote, often auriculiform and a few mm long, sterile; upper pinnules gradually and strongly reduced, confluent into a pinnatifid leaf-apex. Veins immersed, evident, once forked, less often twice forked or simple, 1 or 2 running to each lobe, their ends c. 1 mm apart. Sori uni-or binerval, single on the teeth; indusium pale, subentire, semicircular or reniform to oblong, 0.5-1 mm long, c. 0.3 mm wide, with convex to slightly concave base, not reaching the margin by about its width or more, ± reflexed and sometimes concealed at maturity. Spores pale brown, trilete, smooth, c. 22 μ. Juvenile plants have deeply divided pinnules, but less regularly so than in L. repens.
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