Plants moderate-sized, slender and weak-stemmed, green to pale yellow; flaccid and plumose in aquatic forms to more compact and sprawling in emergent forms; green to pale yellow; capitulum not especially enlarged and differentiated. Stems green; superficial cortex of undifferentiated or slightly differentiated cells. Stem leaves ovate-triangular to triangular, 1-1.6 mm; appressed to spreading; apex acute to slightly obtuse; hyaline cells often fibrillose and often 1-septate. Branches straight and unranked, in capitulum tapering at distal end to a point, leaves greatly elongated at distal end. Branch stems green, cortex enlarged with conspicuous retort cells. Branch leaves ovate-lanceolate to lanceolate, 2-3.5 mm; straight, undulate and slightly recurved when dry; margin serrulate; hyaline cells on convex surface with 0-1 small pores at cell apex on concave surface with round wall thinnings in cell angles (often indistinct or lacking); chlorophyllous cells trapezoidal in transverse section and exposed more broadly on the convex surface. Sexual condition monoicous. Spores 26-40 µm; ± roughly to densely granulose.
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