| 1 | Eublechnoid: sterile and fertile fronds similar on adaxial surface; fertile pinnae either the same width as the sterile or almost so; sorus linear, close to and parallel to the costa but not completely covering the abaxial face leaving a wing of photosynthetic surface |
| 1' | Lomarioid: sterile and fertile fronds distinctive on the adaxial surface; fertile pinnae much narrower than the sterile pinnae; sorus linear, close to and parallel to costa but covering the abaxial face and leaving little or no photosynthetic surface |
| 2 | Stipes and rhachis with spine-like outgrowths |
| 2' | Stipes and rhachis without spine-like outgrowths |
| 3 | Pinnae reduced to small or minute auriculate lobes at the lamina base |
| 3' | Pinnae not reduced to auriculate lobes at the lamina base |
| 4 | Sori often enlarged to overlap or cover the costa and at maturity may obscure the abaxial costal surface; pinnae apices acuminate; fronds of juvenile plants pinnatifid |
| 4' | Sori rarely enlarged to overlap or cover the costa or costal surface; pinnae apices usually attenuate; fronds of juvenile plants entire to lobed |
| 5 | Pinnae articulated with a characteristic socket joint at the rhachis; mature fronds rarely exceeding 100 cm in length; sterile and fertile pinnae 0.5-1.6 cm wide |
| 5' | Pinnae without a socket joint at the rhachis; mature fronds frequently exceeding 100 cm in length; sterile and fertile pinnae 0.7-2.5 cm wide, fertile usually in the narrower range |
| 6 | Sterile pinnae fully or almost fully adnate to the rhachis for entire length of the lamina |
| 6' | Sterile pinnae free at rhachis, at least on basal part of lamina |
| 7 | Lamina margins either not dentate or if so only towards pinna apices; lamina pinnate or pinnatisect |
| 7' | Lamina with conspicuously dentate margins; lamina either pinnate or bipinnate |
| 8 | Lamina veins, costae and rhachis, and sometimes the stipe, with fine straight uniseriate hairs; basal pair of pinnae semi-adnate, falcate and sometimes also deflexed |
| 8' | Lamina without such hairs; basal pair of pinnae not as above |
| 9 | Sterile pinnae reducing to adnate lobes towards the base of the lamina; only dissected fronds known to occur |
| 9' | Sterile pinnae or pinnules adnate to rhachis with bases broadening to lobes or wings of leaf tissue; both entire and dissected fronds known to occur |
| 10 | Sterile pinnae not obviously falcate; margins crenate to finely serrate and may be dentate towards the pinna apices; scales of the rhizome and basal stipe black, concolorous, entire, shiny and with finely acuminate apices |
| 10' | Sterile pinnae slightly to distinctly falcate; margins mostly entire; scales of rhizome and basal stipe dark red-brown, shortly acuminate, some with paler margins |
| 11 | Continuous wing of lamina extending down rhachis below basal pinnae |
| 11' | Discontinuous wing of lamina tissue, or lobes, extending down rhachis below basal pinnae |
| 12 | Adaxial stipe (and sometimes both surfaces of stipe, rhachis, and costae) deeply pigmented purple-black |
| 12' | Adaxial stipe, rhachis, and costae not deeply pigmented |
| 13 | Lamina bipinnate to bipinnatisect; caudex 2-3 cm diam., erect, exceptionally up to 200 cm high, forming a miniature tree-fern |
| 13' | Lamina pinnate to pinnatisect; caudex 1-2 cm diam., and semi-erect often sprawling on the forest floor |
| 14 | Sterile pinnae margins strongly and persistently revolute; lamina densely and persistently scaly throughout with dark mahogany coloured scales intermingled with irregular lanuginose material |
| 14' | Sterile pinnae margins either not revolute or finely revolute; lamina, if scaly, with scales which are relatively thin and pale fawn to ginger-brown |
| 15 | Scales at base of stipe narrowly elliptic to subdeltoid, acuminate, red or purple-black, sometimes with paler borders; upper stipe and rhachis scales thin, ginger-brown, some with a small dark centre; plants with a creeping rhizome giving rise to a succession of fronds but fronds are tufted at the apex of the rhizome |
| 15' | Scales at base of stipe, upper stipe, and rhachis not as above; creeping rhizomes not a conspicuous feature |
| 16 | Sterile pinnae short (less than 4 cm long), rounded to oblong with obtuse apices |
| 16' | Sterile pinnae more than 4 cm long, linear-narrowly elliptic with acute, acuminate or attenuate apices |
| 17 | Sterile pinnae narrowly elliptic; in larger fronds several basal pairs may be petiolate and deflexed; stipe and rhachis often with conspicuous black pigmented lines on the ridges on either side of the adaxial groove |
| 17' | Sterile pinnae oblong-narrowly elliptic, its pinnae sessile, becoming shortly pinnate but not markedly deflexed near the lamina base; stipe and rhachis without black pigmented lines |
| 18 | Pinnae and rhachis densely and usually persistently scaly; scales broadly deltoid, thin, papery, fawn to mid-brown and often weakly bicolorous and intermingled with paler lanuginose scales and variable uniseriate hairs |
| 18' | Pinnae and rhachis either glabrous or with relatively small scales |
| 19 | Basal fertile pinnae sessile or shortly petiolate, with a distinctive expanded, leafy, sterile zone widening towards the rhachis but not as wide as the pinnae of the sterile fronds |
| 19' | Basal fertile pinnae either having no sterile zone, or a very small but not expanded sterile zone, where the pinnae join the rhachis |
