Flora of North America species comparison

leaves ovate-lingulate; 1–1.3 mm, apex broadly rounded;

hyaline cells nonseptate, aporose and fibrillose in at least distal half of leaf.

leaves long triangular-ovate, 1–2 mm; usually appressed;

apex acute to apiculate, hyaline cells only rarely septate or aporose but often fibrillose in apical region.

2–3 spreading and 2 pendent leaves not much elongated at distal end.

unranked, straight to slightly curved, leaves somewhat elongated at distal end.

ovate, 1–1.5 mm; straight;

not or weakly undulate or recurved when dry;

margins entire;

hyaline cells short and wide, convex surface with 1–3 small pores per cell and on concave surface with large round wall thinnings in the cell angles; chlorophyllous cells equilateral-triangular in transverse section, broadly exposed on convex surface and just reaching to well-enclosed on concave surface.

1.5–2.7 mm, ovate-lanceolate to lanceolate; straight to falcate toward branch tips; when dry often undulate and lightly recurved, margins entire to rarely weakly toothed along the margins in flaccid aquatic forms, hyaline cells on convex surface with 0–1 small round pores at apex, on concave surface with faint round wall thinnings in cell apices and angles; chlorophyllous cells triangular to trapezoidal in transverse section, broadly exposed on the convex surface and exposed slightly to broadly on the concave surface.

monoicous.

dioicous.

27–42 µm;

both surfaces smooth, proximal surface with distinct bifurcated Y-mark sculpture surrounded by distinct circular border, distal surface with distinct raised border around margins;

proximal laesura usually less than 0.4 spore radius.

30–43 µm; the superficial surface coarsely papillose to papillose reticulate.

stems green;

cortex enlarged, with conspicuously long-necked retort cells.

fascicles with 2 spreading and 2–3 pendent branches.;

branch stems green, cortex enlarged with conspicuous retort cells.