Flora of North America species comparison

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.

leaves lingulate to lingulate-triangular, 0.7–1.5 mm (to 3 mm in isophyllous forms), apex erose;

hyaline cells mostly 1–septate but in a few cells with 2–3 parallel septations, efibrillose to fibrillose throughout, pores present in hemiisophyllous and isophyllous forms.

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

straight to somewhat curved, with spreading leaves.

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.

variable, broadly ovate to ovate-lanceolate, 1.3–5 mm; straight, hyaline cells on the convex surface with 4–8 µm round to elliptic pores in nearly continuous rows along the commissures, the concave surface aporose or with some porosity as on the convex surface.

dioicous.

unknown.

not seen.

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

not seen.

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

branch stems green, cortex enlarged with conspicuous retort cells.

fascicles with 2 spreading and 2 pendent in emergent forms, these reduced in aquatic forms to 2 per fascicle.