Flora of North America species comparison

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

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

leaves triangular-lingulate, 0.8 mm or less;

apex entire or weakly denticulate, hyaline cells sometimes septate, efibrillose and aporose except near apex.

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

often short and blunt.

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.

exserted, with few pseudostomata.

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

proximal laesura less than 0.5 spore radius.

30–35 µm; finely papillose on both surfaces, distinct bifurcated Y-mark sculpture on distal surface;

proximal laesurae more than 0.5 spore radius.

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.

fascicles with 2–3 spreading and 2–3 pendent branches Branch leaves broadly ovate, subsecund, hyaline cells on convex surface with very numerous small pores (18–40 per cell) in a continuous row along the commissures, concave surface usually aporose.