Flora of North America species comparison

elongate, 4–9 × 2–5 mm;

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

squarish in face view, 2–5(–10) × 2–5(–9) mm;

teeth dark, 4–14, narrow, 1–3.5 mm, often cohering in pairs.

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, 2–60(–100) cm;

hollow center 1/3–2/3 stem diam.

brown, lacking stomates, unbranched, shorter than vegetative stems, with larger sheaths, fleshy, ephemeral.

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, ascending, solid;

ridges 3–4;

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

sheath teeth attenuate.

=216.

=ca. 216.