Greek phymatos, swelling, + soros, heap, in reference to the appearance of the usually raised sori.
Plants medium-sized to large, terrestrial or occasionally epiphytic. Rhizomes long-creeping, clothed with scales. Fronds remote, articulate. Stipes light brown to straw-colored. Blades entire, lobed, or pinnatisect. Veins obscure, anastomosing extensively to form areoles with branching included veinlets, these ending in swollen tips. Sori exindusiate, round to elliptic, slightly sunken and causing raised convex bumps on upper blade surface, in 1-2 (-3) rows on either side of costae.
A genus of about ten species distributed from Africa, Madagascar and the Mascarenes to Asia, Australia, and the South Pacific.
The genus is identifiable by its long-creeping rhizomes and large sori borne in rows in cavities on the undersides of fronds, appearing raised on upper surfaces. Represented in Hawai 'i by a single naturalized species.
