Plants robust and weak-stemmed; green to golden yellow; capitulum ± rounded in emergent forms, flat in submersed forms; lacking distinct terminal bud. Stems green to brown; superficial cortex of 2 layers of thin-walled and enlarged cells. Stem leaves triangular, 1-1.7 mm, apex acute to slightly obtuse; leaves usually appressed; margins entire; hyaline cells fibrillose and usually septate at base and sides. Branches unranked, long and tapering, leaves greatly elongated at distal end. Branch fascicles with 2 spreading and 2 pendent branches. Branch stems green; cortex enlarged with conspicuous retort cells. Branch leaves ovate-lanceolate to lanceolate, 3-5.5 mm; straight but sometimes slightly falcate-secund; weakly undulate and recurved when dry; margins entire; hyaline cells on convex surface with 0-1 pore per cell, on concave surface with round wall thinnings on the apices and angles; chlorophyllous cells narrowly triangular in transverse section and just enclosed on the concave surface. Sexual condition dioicous. Spores 26-29 µm; both surfaces distinctly papillose, appearing pusticulate to irregularly pusticulate; proximal laesura mostly less than 0.5 spore radius.
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