Lygodiaceae M.Roem.

Climbing ferns. Rhizomes creeping, bearing septate hairs. Fronds monomorphic, not articulated to rhizome; juvenile fronds of determinate growth; adult fronds twining and climbing with a wiry rachis of indeterminate growth. Stipes glabrous or hairy. Pinnae arising alternately on rachis, dividing pseudo-dichotomously with a dormant bud in the axil, glabrous or sparsely hairy. Fertile and sterile segments often markedly dimorphic. Veins free or reticulate without free included veinlets. Sporangia borne individually in two rows on marginal lobes of the fertile segments, not in sori, each covered by an antrorse subtending indusium-like flange, asymmetrically ovoid, attached laterally, with the annulus horizontal around the outward-pointing apex, dehiscing by a vertical longitudinal slit; spores maturing ±simultaneously; 128–256 spores per sporangium. Homosporous; spores trilete, tuberculate or verrucate, lacking chlorophyll.

A family of one genus and about 30 species. Earlier classifications have varied in their treatment of the Schizaeales. Allan (1961) and Kramer (1990) included the Lygodiaceae and Anemiaceae in the Schizaeaceae, whereas Pichi Sermolli (1977) maintained all three as separate families. Three families are now generally recognised within the Schizaeales (Smith et al. 2006; Christenhusz et al. 2011).

The Lygodiaceae are climbing ferns recognised by their creeping rhizomes bearing septate hairs, adult fronds of indeterminate growth, pseudo-dichotomously branching pinnae, markedly different fertile and sterile segments, sporangia borne on marginal lobes of the segments, not in sori, each sporangium protected by a subtending flange, and a base chromosome number of 29 or 30.