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DescriptionSmall floating ferns, whole plant oblong to deltoid in outline, up to 20 × 15 mm. Rhizome up to 0.2 mm in diameter, horizontal, branched into 3-5 alternate pinnae. Roots single or in fascicles of 2-3 at the branche nodes, up to 3.5 cm long, hairy, with conspicuous root cap. Leaves minute in 2 rows, dark green, 2-lobed; upper lobe up to 1.1 mm long, ovate to broadly elliptic in outline, apex pointed, papillate in the centre and with a hyaline border; lower lobe colourless, more or less equal in size. Plant heterosporous, sporocarps on the submerged lower lobes of the leaves.