Flora of North America species comparison

fibrous, principally adventitious.

obscurely to ca. 10-ribbed when dry, terete, 1–12 cm × 0.4–1 mm, very soft, spongy.

(culms) usually trigonous, occasionally terete, rarely compressed, usually solid, rarely hollow or septate.

distal leaf sheaths fugaceous, colorless, translucent, apex blunt.

basal and/or cauline, alternate, usually 3-ranked, rarely 2-ranked or multi-ranked, bases forming cylindric sheaths enclosing stem, margins usually fused;

junction of sheaths and blades often with adaxial flaps of tissue or fringes of hair (ligules);

blades frequently absent from some basal leaves, rarely from cauline leaves, when present divergent or ascending, flat, folded, plicate, rolled, or terete, linear, venation parallel.

ovoid, 2–3 × 1–1.5 mm, apex acute;

scales 5–15, 5–7 per mm of rachilla, colorless to stramineous, rarely slightly reddish, medially broadly greenish to colorless, faintly 3–5-veined, often ovate, membranous, fleshy;

proximal scale 2–2.5 × 0.7 mm, other scales 1.5–2 × 0.7 mm, midrib obscure to slightly keeled, apex acute to rounded.

perianth bristles equaling achene;

anthers yellow to brown, 0.3–0.5 mm.

hypogynous, bisexual in most genera, unisexual in Scleria, Carex, Cymophyllus, and Kobresia;

perianth absent or with (1–)3–6(–30) bristles and/or scales, usually falling off with fruit;

stamens usually (1–)3, rarely more, usually distinct;

anthers basifixed;

pistils 1, 2–3(–4)-carpellate, fused, locule 1;

style undivided or branches 2–3(–4);

stigma sometimes papillate.

achenes, usually trigonous or biconvex;

pericarps thin (except in Scleria).

brownish, angles plus longitudinal ridges ca. 7, narrowly obovoid, 2 times longer than wide, 0.75–0.9 × 0.35–0.4 mm, trabeculae ca. 50, distinct.

1;

testa thin, free from pericarp;

embryo basal;

endosperm abundant.

brown, pyramidal, 0.15 × 0.15–0.2 mm.

inflorescences (spikelets) a shortened axis; glumaceous bracts (scales) 1–many, spirally arranged, sometimes 2-ranked, usually appressed or ascending;

scales usually all fertile, each subtending a single flower, sometimes proximal and/or distal scales empty;

lateral spikes often with basal, usually empty, usually 2-keeled scale (prophyll); occasionally prophyll subtending and enclosing rachilla, bearing 1 pistillate, sometimes (0–)3 staminate flowers and empty scales (Carex, Cymophyllus, and Kobresia).

inflorescences panicles, often modified to corymb, pseudoumbel, cyme (anthela), raceme, spike, or capitulum (head), rarely single spike, usually subtended by foliaceous or, less frequently, glumaceous bracts;

secondary inflorescences sometimes simulating spikelets (Carex, Cymophyllus, and Kobresia).

= 5–ca. 100.