Teratophyllum Mett. ex Kuhn

Rhizome scandent, dorsiventral, bearing on the ventral surface roots only and on the dorsal surface fronds alternately in 2 rows (sect. Teratophyllum) or at maturity in several rows (sect. Polyseriatae); bases of stipes swollen and ± articulate to rhizome; rhizome-scales small, peltate, appressed, fugacious, not clathrate. Fronds of young plants, or on branches of old plants near ground level (bathyphylls) of a distinctive form characteristic of each species, often bipinnate, with winged rachis and pinnae jointed to it; fronds of high-climbing rhizomes (acrophylls) larger, simply pinnate (sect. Teratophyllum) or sometimes bipinnate (sect. Polyseriatae), all pinnae (including the apparently apical one) subequal and jointed to rachis; veins in sterile pinnae or pinnules free, simple or forked; scales small, peltate, with marginal hairs ending in glandularcells; fertile pinnae or pinnules much narrower than sterile, their lower surfaces covered with sporangia, the lamina thicker than that of sterile leaflets and containing an additional vascular system close to the surface which bears the sporangia, the strands of this vascular system often anastomosing; paraphyses like the small scales on sterile frond but with a stalk of 5-8 cells; spores with folded perispore.