1 | A tooth present in each sinus between lobes of lamina, the tooth not in the plane of the lamina. |
1' | No tooth present in sinuses between lobes of lamina. |
2 | Vascular bundles in stipes numerous, not in a simple ring; veins more or less anastomosing. |
2' | Vascular bundles in stipes in a simple ring; veins free |
3 | Veins anastomosing in a single series of costal and costular areoles. |
3' | Veins more copiously anastomosing |
4 | Pinnae jointed to rachis |
4' | Pinnae not jointed to rachis. |
5 | Fertile leaflets acrostichoid and very much contracted as compared with sterile ones. |
5' | Fertile leaflets not acrostichoid. |
6 | Veins free; sterile frond much divided |
6' | Veins anastomosing. |
7 | Fronds deltoid, the basal basiscopic lobe of basal pinnae largest. |
7' | Fronds otherwise, basal basiscopic lobes of basal pinnae not largest. |
8 | Fronds small, trifoliate; apical leaflet largest, commonly 5 cm long. |
8' | Fronds larger and in most cases more divided. |
9 | Sterile fronds simple to deeply pinnatifid, not truly pinnate. |
9' | Sterile fronds with at least one pair of free pinnae, usually several pairs |
10 | Two vascular bundles in base of stipe, uniting upwards to form a single bundle; scales confined to swollen bases of stipes |
10' | More than two vascular bundles throughout length of stipe; scales not so confined. |
11 | Veins free. |
11' | Veins anastomosing. |
12 | Basal basiscopic vein of a vein-group springing from the costule. |
12' | Basal basiscopic vein of a vein-group springing directly from the costa. |
13 | Indusia peltate |
13' | Indusia reniform or absent. |
14 | Fronds usually much longer than wide; basiscopic margin of lamina-lobes not thickened. |
14' | Fronds usually about as long as wide; basiscopic margin of lamina-lobes thickened. |
15 | Basal pinnae with basal basiscopic lobes longest |
15' | Basal pinnae with basal basiscopic lobes or pinnules shorter than middle ones. |
16 | Sori large, indusiate, terminal on a free vein, the receptacle elongate, fertile fronds narrow. |
16' | Sori various, indusiate or not, on free or netted veins; if indusiate, the receptacle not elongate, or fertile fronds not contracted as compared with sterile. |
17 | Basal pinnae deeply lobed, basal basiscopic lobe not largest; few free veins in areoles. |
17' | Basal pinnae lobed or not; if lobed, basal basiscopic lobe largest; many free veins in areoles. |