Lindsaea-group

Small to medium-sized, rarely large, terrestrial or epiphytic ferns. Rhizome creeping, terrestrial and radially symmetric or nearly so, solenostelic or more often with a special type of protostele with internal phloem but without internal endodermis and medulla; or epiphytic and with a similar but strongly dorsiventral protostele with the internal phloem close to the dorsal side of the xylem, or in some small species the xylem strand open and U-shaped. Petioles with a single U- or V-shaped vascular bundle. Indument of the rhizome of scales, these nonpeltate, non-clathrate (in Mal. spp.), glabrous, entire, or with weakly developed teeth of two protruding cell-ends; terminal cell of scale glandular. Juvenile leaves with similar but narrower, caducous scales. In some species some or even all scales are entirely uniseriate but not true hairs. Laminal parts with scattered microscopical two-celled hairs, hardly ever with macroscopically visible hairs. Axes of leaves adaxially with a single groove bordered by ridges, both mostly continuous with those on axes of different order. Lamina once pinnate to decompound (rarely simple in a single Old World sp.), anadromous. Ultimate divisions various, often dimidiate. Veins free, or reticulate without free included veinlets, not reaching the margin. Sori terminal on one to many veins, often on a commissure ± parallel to the margin, submarginal, indusiate; indusium attached at its base, the sides free or adnate, the free edge next to the leaf-margin and often ± equaling it. Sporangia ± long-stalked, with a triseriate stalk; bow of annulus interrupted; stomium well differentiated or not. Spores trilete or less often monolete, without perisporium, smooth or with little sculpture. Paraphyses mostly, perhaps always, present, filiform, 2- to many-celled, often early disappearing. Gametophyte known in very few species, cordate. Distribution. Pantropic, extending considerably beyond the tropics in Japan, Australia, South Africa, and eastern South America; comparatively weakly represented in continental Africa. Six genera: Odontosoria (10 American spp., 2 African spp.), Ormoloma (2 spp., neotropical), Tapeinidium (17 spp., SE. Asia to Samoa), Sphenomeris (11 spp., pantropic-subtropic), Xyropteris (monotypic, Malesian), and Lindsaea (c. 150 spp., pantropic-subtropic)