| 1 | Small scales on frond stellate or elongate, their marginal hairs glandularor with a glandularapical cell, thick-walled unicellular marginal hairs lacking; rhizome-scales various. |
| 1' | Small scales on frond (except near edge) ± orbicular, pale, with marginal teeth or hairs each of one thick-walled cell, not glandular; rhizome-scales always narrow, rigid, dark, glossy. |
| 2 | Lamina of sterile fronds rarely over 7 cm long; rhizome 1-2 mm ø, fronds usually well-spaced on it. |
| 2' | Lamina of sterile fronds usually more than 7 cm long; rhizome thicker. |
| 3 | Rhizome-scales light brown. |
| 3' | Rhizome-scales dark |
| 4 | Sterile lamina elliptic, commonly 4-7 cm long, base decurrent as a narrow wing. |
| 4' | Sterile lamina ovate, almost same shape and size as fertile, c. 2 cm long. |
| 5 | Fertile lamina spathulate, abruptly contracted at base and then decurrent as a narrow wing 2 cm long; rhizome-scales to 1 mm wide |
| 5' | Fertile lamina narrowly elliptic, little decurrent; rhizome-scales 2 mm wide |
| 6 | Rhizome long-creeping with well-spaced fronds. |
| 6' | Rhizome short, with closely-placed fronds. |
| 7 | Apex of sterile fronds acute or short-acuminate. |
| 7' | Apex of sterile frond rounded. |
| 8 | Scales dark, glossy, 1 mm wide |
| 8' | Scales thin, medium brown, 2-3 mm wide |
| 9 | Rhizome-scales light brown; scales on frond red-brown |
| 9' | Rhizome-scales dark brown; scales on frond dark, glossy (not known in no 9). |
| 10 | Rhizome-scales to 5 by 1.5 mm; stipe of sterile fronds 4-15 cm long. |
| 10' | Rhizome-scales shorter, less than 1 mm wide; stipe of sterile fronds 3-5 cm. |
| 11 | Lamina of sterile frond decurrent to joint with phyllopodium or within 2 cm of joint. |
| 11' | Lamina of sterile frond not thus decurrent. |
| 12 | Edge of sterile lamina conspicuously pale and thin, 0.5 mm or more wide. |
| 12' | Edge of sterile lamina not conspicuously pale and thin. |
| 13 | Sterile lamina twice as wide as fertile. |
| 13' | Sterile lamina little wider than fertile |
| 14 | Apex of sterile frond bluntly pointed or rounded, base cuneate and then decurrent for 4-7 cm as a wing 1-2 mm wide on each side of costa |
| 14' | Apex of sterile frond short-acuminate, base narrowed evenly almost to joint with phyllopodium |
| 15 | Sterile frond acuminate or apiculate. |
| 15' | Sterile frond not acuminate nor apiculate. |
| 16 | Rhizome-scales 10-15 by 3-4 mm, light brown, thin; lamina widest above middle |
| 16' | Rhizome-scales much smaller, dark; lamina widest at middle. |
| 17 | Sterile frond c. 22 by 2 cm |
| 17' | Sterile frond much larger, to 4½ cm wide. |
| 18 | Apex of sterile frond acuminate. |
| 18' | Apex of sterile frond broad with a narrow apiculus 5 mm long. |
| 19 | Sterile frond 35-50 by 3.5-5 cm |
| 19' | Sterile frond to 35 by 2.3 cm |
| 20 | Sterile frond widest 1/3 from apex, narrowed rather abruptly to broad-pointed apex. |
| 20' | Sterile frond widest about middle, or if above middle narrowed gradually to a rounded apex. |
| 21 | Rhizome-scales 15-20 mm long, 2 mm wide; fronds thick, veins obscure; costa broad and little prominent on lower surface |
| 21' | Rhizome-scales not over 10 mm long; fronds rather thin, veins distinct; costa slender and prominent on lower surface. |
| 22 | Scales on surface of frond pale, bearing slender hairs 1 mm long; stipe of fertile frond 10-15 cm |
| 22' | Scales on frond dark, bearing very short hairs; stipe of fertile frond 25-30 cm |
| 23 | Sterile frond widest at middle, apex acute; fertile frond to 2 cm wide |
| 23' | Sterile frond widest a little above middle, gradually narrowed to rounded apex; fertile fronds not over 1.3 cm wide |
| 24 | Scales on rhizome dark, rigid, glossy. |
| 24' | Scales on rhizome medium to light brown, mostly rather thin. |
| 25 | Small scales on upper surface of frond dark, glossy, elongate, with dark rigid cylindrical marginal hairs each consisting of one cell with a small thin-walled cell at its apex. |
| 25' | Small scales on upper surface otherwise, at least some of their marginal hairs multicellular with glandular apical cell. |
| 26 | Scales on lamina 1-2 mm long; fronds with broadly rounded apex. |
| 26' | Scales on lamina much smaller; apex of fronds not broadly rounded. |
| 27 | Apex of sterile frond rounded. |
| 27' | Apex of sterile fronds acute or acuminate. |
| 28 | Phyllopodia ½-1 cm long; lamina of sterile frond always c. 10 times as long as wide. |
| 28' | Phyllopodia 1.5-2 cm long; lamina of sterile frond often proportionately broader |
| 29 | Scales on costa and stipe appressed, on lamina very small |
| 29' | Scales on stipe and costa spreading, on lamina 1-2 mm long, abundant |
| 30 | Lamina of sterile frond c. 10 times as long as wide. |
| 30' | Lamina of sterile frond c. 5 times as long as wide. |
| 31 | Rhizome-scales less than 1 mm wide, somewhat crisped; stipe of fertile frond not or little longer than that of sterile |
| 31' | Rhizome-scales more than 1 mm wide, flat; stipe of fertile frond usually twice as long as sterile. |
| 32 | Sterile frond 3.5-5 cm wide, 35-50 cm long |
| 32' | Sterile frond to 2.3 cm wide, 35 cm long |
| 33 | Rhizome bearing fronds 5-10 mm apart; scales 6 by 1 mm; sterile lamina widest below middle, rather abruptly contracted at base, apex short-pointed. |
| 33' | Rhizome bearing fronds close together; scales 10 by 1.5 mm; sterile lamina widest at middle, base rather narrowly cuneate, apex acuminate |
| 34 | Lower surface of sterile lamina covered with a feit of narrow scales 2-3 mm long |
| 34' | Lower surface of lamina bearing smaller, usually appressed, scales. |
| 35 | Fronds of adult plants widest above middle, with rounded apices and decurrent bases. |
| 35' | Fronds of adult plants, if widest above middle, rather much narrowed upwards, apex not broadly rounded. |
| 36 | Fronds lacking a fringe of spreading scales. |
| 36' | Fronds bearing a fringe of spreading scales |
| 37 | Rhizome-scales less than 1 mm wide |
| 37' | Rhizome-scales 2 mm or more wide |
| 38 | Sterile fronds with distinct thin pale edge which bears abundant scales 1-1.5 mm long, persistent on young plants, mostly lost on old ones |
| 38' | Sterile fronds without a fringe of scales. |
| 39 | Sterile lamina twice as long as wide (to 12 by 6 cm); stipe of fertile frond as long as sterile frond with its stipe |
| 39' | Not this combination of characters. |
| 40 | Apex of sterile frond distinctly pointed, point broad or acute. |
| 40' | Apex of sterile frond distinctly rounded. |
| 41 | Sterile frond widest in distal half, base very gradually and evenly narrowed, stipe to 5 cm long |
| 41' | Sterile frond widest at or below middle, base otherwise, stipe in most cases longer. |
| 42 | Pale margin of sterile frond thin, flat, 0.5 mm wide or nearly so. |
| 42' | Pale margin of sterile frond very narrow, usually reflexed. |
| 43 | Fronds widest below middle, narrowed gradually to apex; veins distinct |
| 43' | Fronds widest at middle, apex obtuse-angled; veins not distinct |
| 44 | Scales to 1.5 mm wide, not flat. |
| 44' | Scales wider, flat or little crisped, edges not inrolled. |
| 45 | Scales straight and rather stiff with inrolled edges; frond commonly 35 cm or more long, narrowly elliptic |
| 45' | Scales thin, crisped throughout, with long twisted hair-points; frond rarely 30 cm long, broadly elliptic |
| 46 | Stipe of fertile frond not much longer than stipe of sterile. |
| 46' | Stipe of fertile frond at least twice as long as stipe of sterile. |
| 47 | Scales commonly 20-25 by 2.5-3 mm |
| 47' | Scales not over 10 mm long. |
| 48 | Rhizome-scales with many spreading marginal hairs; scales on lamina to 1 mm long, narrow |
| 48' | Rhizome-scales with few marginal hairs; scales on lamina stellate, under ½ mm long. |
| 49 | Costa broad and not prominent beneath; rhizome-scales firm |
| 49' | Costa prominent beneath; rhizome-scales thin, with isodiametric cells |
| 50 | Scales 6 by 2.5 mm, sterile frond short-acuminate. |
| 50' | Scales to 15 by 2 mm; sterile frond broadly pointed |
| 51 | Rhizome-scales 3-5 mm long; fertile frond c. 8 by 3.3 cm |
| 51' | Rhizome-scales 10-15 mm long; fertile frond at least 6 times as long as wide. |
| 52 | Spores 52-59 μm long with broad perispore of few folds; stipe of fertile frond twice as long as that of sterile; edge of lamina thick, deflexed; lamina greenish when dry. |
| 52' | Spores c. 37 μm long with narrow much-folded perispore; stipe of fertile fronds not much longer than of sterile; pale edge of lamina thin; fronds brownish when dry, thick, rigid |
| 53 | Lamina of sterile frond to 30 by 5 cm, stipe 5-8 cm long. |
| 53' | Lamina of sterile frond 35-55 cm long, stipe 14-18 cm long. |
| 54 | Scales on upper surface conspicuously stellate; sterile fronds often to 3 cm wide. |
| 54' | Scales on upper surface with very short marginal hairs; sterile fronds c. 1 cm wide |
| 55 | Scales on lower surface very small, each with 3-5 marginal hairs ½-1 mm long spreading away from frond-surface |
| 55' | Scales on lower surface with a distinct lamina (flat or not) bearing more slender and shorter marginal hairs. |
| 56 | Scales of lower surface mostly elongate, bullate at base; on upper surface flat, those near margin elongate, forming a conspicuous spreading fringe |
| 56' | Scales of lower surface small, orbicular, flat or cup-shaped; scales of upper surface flat, about same size as on lower, those near margin not forming a conspicuous fringe |
