1Indusia rather large, persistent; lamina thin, veins slender, slightly prominent on both sides.
1'Indusia small, almost hidden by sporangia at maturity of sorus, or apparently lacking; lamina firm, veins not prominent on either.surface.
2Caudex long-creeping; pinnae lobed half-way to costa or less deeply; apex of frond ± pinna-like
2'Caudex short-creeping or erect; pinnae lobed more than half-way to costa; apex of frond not pinna-like.
3Pinnae lobed to 1 mm from costa or more deeply; basal veins free or uniting to form very short excurrent veins.
3'Pinnae lobed less deeply; basal veins anastomosing to form an excurrent vein on most parts of a frond
4Basal veins not meeting; sori in slight depressions
4'Basal veins meeting just below the sinus, sometimes forming a short excurrent vein; sori not immersed
5Hairs more than 0.5 mm long present on both sides of costa; stipe and abaxial surface of rachis bearing scales throughout
5'All hairs on costa very short; scales confined to base of stipe.
6Lower surface between veins (sometimes in part) bearing very short erect acicular hairs; short capitate hairs also in this position on the upper surface
6'Both surfaces lacking hairs between veins.
7Pinnae lobed to c. 2 mm from costa, basal veins often anastomosing.
7'Pinnae lobed more deeply; basal veins not anastomosing.
8Many glandular hairs on lower surface between veins, some spherical, some ± elongate; similar hairs also on indusia
8'Glandularhairs less abundant, always spherical, tending to collapse and form resinous patches or to disappear on drying
9Pinnae thin, to 3 cm wide; glands on lower surface of pinnae and on indusia elongate
9'Pinnae firm, to 1.5 cm wide; glands on lower surface glabular to pyriform, on indusia spherical, resinous