Flora of North America species comparison

green to red;

superficial cortical cells aporose Stem leaves lingulate-triangular, 1.2–1.6(–1.8) mm, apex ± involute;

border entire and broadened to about 0.25 the width of the base;

hyaline cells S-shaped, 0–1-septate, usually fibrillose in distal portion of leaf.

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

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

not 5-ranked, terete.

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

ovate-lanceolate, 1–1.4 mm, imbricate to moderately spreading, concave, straight, strongly involute near apex;

hyaline cells on convex surface with elliptic pores along commissures, concave surface with large round pores away from commissures in proximal portions of leaf.

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.

20–28 µm; finely papillose on both surfaces, with distinct raised Y-shaped sculpture on distal surface;

proximal laesura 0.5 spore radius or more.

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

proximal laesura less than 0.5 spore radius.

fascicles with 2 spreading and 1–2 pendent branches.

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.