Flora of North America species comparison

elongate, 4–9 × 2–5 mm;

teeth dark, 5–10, narrow, 2–5 mm, margins white, scarious.

somewhat elongate, 3–5 × 2–4 mm;

teeth 8–18, narrow, 1.5–4 mm, centers dark and margins white.

monomorphic, green, branched or unbranched, 20–80 cm;

hollow center small, to 1/3 stem diam.;

vallecular canals nearly as large.

dimorphic;

vegetative stems green, branched, 16–50 cm;

hollow center 1/6–1/3 stem diam.

brown, with stomates, initially unbranched, persisting and becoming branched and green after spore discharge.

when present only from midstem nodes, spreading, hollow;

ridges 4–6;

valleys rounded; 1st internode of each branch shorter than subtending stem sheath;

sheath teeth narrow.

in regular whorls, horizontal to drooping, solid;

ridges 3;

valleys channeled; 1st internode of each branch equal to or longer than subtending stem sheath;

sheath teeth deltate.

=216.