Flora of North America species comparison

leaves to 2 × 0.7 mm; rarely hemiisophyllous;

hyaline cells non-ornamented, mostly nonseptate.

leaves triangular-ovate, more than 1.2 mm, usually appressed;

apex acute to apiculate, hyaline cells rarely septate or porose, apical region often fibrillose.

long and tapering to short and pointed, leaves loosely imbricate.

mostly unranked to weakly 5-ranked, often conspicuously falcate, leaves greatly elongated at distal end.

broadly ovate, to 2 × 1 mm or more wide, broadly ovate, hyaline cells non-ornamented, convex surface with round to elliptic pores along the commissures; chlorophyllous cells short-elliptic in transverse section and well-enclosed on both surfaces.

ovate-lanceolate to lanceolate, 1.6–5 mm, falcate toward branch tips, when dry often undulate and recurved, rarely weakly serrulate along the margins in submerged forms, leaves from middle of spreading branches with length to width ratio less than or equal to 1:0.28;

hyaline cells length to width ratio in apical convex surface region 8:1 or more, convex surface with 0–1 small round pores at apex, 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 on the concave surface.

dioicous.

dioicous.

with numerous pseudostomata.

22–30 µm; roughly papillose to nearly smooth, with distinct Y-mark sculpture on distal surface;

proximal laesura 0.5–0.8 spore radius.

29–38 µm; covered with large papillae on both surfaces, appearing pusticulate;

proximal laesura less than 0.5 spore radius.

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

branch stems with hyaline cells non-ornamented;

no or weak funnel-like projections on the interior end walls, large round pores on superficial cell walls.

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

branch stems green, but often pinkish at the proximal ends, with cortex enlarged with conspicuous retort cells.