or epilithic ferns. Rhizome thick, short or long creeping, covered with
oppressed or spreading scales. Stipe absent or dilated. Fronds internally
dimorphic or monomorphic, sessile with a dilated base or stalked, frond bases
imbricated or separate, forming individual nests. Lamina pinnatified or
pinnate. Pinnae articulated to the rachis by an abscission vein, gradually
smaller towards the frond apex, entire, apical pinna present. Venation highly
complex. Sorus small, in rows along connecting veins or veins-lets, or
distinctly enlarged to soral patches.