1 Leaves pinnate-pinnatifid, each pinna additionally pinnatifid but not divided into distinct pinnules; spores borne either on specialized leaves that are normally wholly fertile (lacking flat, blade-like sterile pinnae), or hemidimorphic (juvenile leaves with only sterile pinnae, adult leaves with both sterile and fertile pinnae, the fertile pinnae borne in the middle of the leaf with sterile pinnae above and below; photosynthetic (sterile) pinnae lacking tufts of hairs; veins of each pinna lobe 1× Y-forked (thus each vein reaching the margin as 2 final veinlets), the final veinlets not creating a tooth, thus the pinna lobes entire to obscurely crenulate.