KEY TO THE SPECIES OF THE PHILIPPINES

1Sori more or less regularly spaced, either in a single row between costa and margin, or in two, sometimes irregular rows between the lateral veins
1'Sori irregularly scattered on the lamina surface
2Lamina pinnatifid
2'Lamina simple or irregularly lobed
3Rhizome white waxy, with sclerified circumvascular sheaths and scattered sclerenchyma strands
3'Rhizome not white waxy, with either scattered sclerenchyma strands, or scleri-fied circumvascular sheaths
4Sori superficial or slightly immersed, in one to several rows between costa and margin, scales peltate
4'Sori deeply sunken, visible as protrusions on upper surface, in one row, generally close to the costa, at most halfway to the margin, scales pseudopeltate
5Apex of lobes rounded or acute, rhizome dorsiventrally flattened, with sclerified circumvascular sheaths, lamina herbaceous, margin entire
5'Apex of lobes long-acuminate, the rhizome terete, with scattered sclerenchyma strands, lamina membranaceous, margin undulate
6Rhizome white waxy, sori deeply sunken, visible as protrusions on the upper surface
6'Rhizome not white waxy, sori superficial or slightly immersed
7Scales round or elliptic, peltate, 0.8-1.2 mm long, often with eroded margins, roots sparsely set
7'Scales (narrowly) ovate or triangular, pseudopeltate, 1.5-6.5 mm long, margins usually intact, roots densely set
8Lamina base narrowly angustate, decurrent into a long wing, rhizome with sclerified circumvascular sheaths and scattered sclerenchyma strands, sori in two (irregular) rows between each pair of veins
8'Lamina base truncate-angustate or cuneate-angustate, rhizome with only scattered sclerenchyma strands or not sclerified at all, one row of sori between costa and margin, generally close to the costa, at most halfway to the margin.
9Rhizome without sclerenchyma strands or sclerified circumvascular sheaths.
9'Rhizome with circumvascular sclerified sheaths or scattered strands of sclerenchyma
10Rhizome with only scattered strands of sclerenchyma, rhizome white waxy underneath the scales
10'Rhizome with circumvascular sheaths, rhizome not white waxy underneath the scales
11Rhizome with circumvascular sclerified sheaths and scattered strands of sclerenchyma
11'Rhizome with only circumvascular sheaths
12Sclerenchyma strands 50-100, scales densely set, slightly to distinctly spreading, phyllopodia 1.5-6 cm apart, lamina herbaceous
12'Sclerenchyma strands 8-15, scales apically densely set, elsewhere more sparsely set, appressed, phyllopodia to 1.1 cm apart, lamina thin-herbaceous.
13Venation with one row of large areoles parallel to the costa, costal areole, if present, formed by smaller veins
13'Venation with several rows of more or less equally sized areoles between costa and margin, costal areole, if present, formed by included veinlets
14Lamina pinnatifid or bipinnatifid, lower surface without acicular hairs.
14'Lamina simple, lower surface with acicular hairs
15Lamina base truncate, not decurrent into a long wing, scales slightly spreading, phyllopodia obscure, lamina herbaceous or subcoriaceous, included veins more or less immersed and indistinct
15'Lamina base narrowly angustate, decurrent into a long wing, scales appressed, or distinctly spreading, phyllopodia more or less elevated, lamina thin-herbaceous, all veins prominent and distinct
16Roots sparsely set, scales densely set, lamina margin sinuate, veins more or less immersed and indistinct
16'Roots densely set, scales apically densely set, elsewhere more sparsely set, lamina margin entire, veins prominent and distinct
17Scales in central region glabrous, margin entire or denticulate, phyllopodia more or less distinct, lamina thin-herbaceous, base narrowly angustate, decurrent to a long wing, connecting veins 1-3, between midrib and margin, mainly anadromous
17'Scales in central region bearing hairs at least when young, margin dentate, phyllopodia not elevated, lamina herbaceous, base truncate or cuneate, connecting veins 4-7 between midrib and margin, catadromous