Flora of North America species comparison

annual or perennial, not woody, branches 1 to many at the upper nodes.

10-200 cm, herbaceous, not branching at the upper nodes;

basal branching usually intravaginal;

prophylls shorter than the sheaths.

basally concentrated to evenly distributed;

sheaths open, margins not fused, sometimes ciliate distally, basal sheaths sometimes concealing axillary panicles (cleistogenes), sometimes wider than the blade;

collars sometimes with tufts of hair at the sides extending to the top of the sheaths;

auricles absent;

ligules scarious, often ciliate, cilia usually shorter than the base, ligules of the lower and upper cauline leaves sometimes differing in size and vestiture;

pseudopetioles absent;

blades linear to narrowly lanceolate, venation parallel, cross venation not evident, cross sections non-Kranz, without arm or fusoid cells;

epidermes of adaxial surfaces sometimes with unicellular microhairs, cells not papillate.

mostly basal;

cleistogenes usually not developed;

sheaths open;

auricles absent;

ligules membranous, sometimes stiffly so, upper and lower ligules similar or upper ligules longer than those below;

blades prominently ribbed, usually tightly convolute when dry.

usually terminal panicles, occasionally reduced to racemes in depauperate plants, sometimes 2-3 panicles developing from the highest cauline node.

terminal panicles, usually contracted.

usually with 1 floret, sometimes with 2-6 florets, laterally compressed to terete;

rachillas not prolonged beyond the base of the floret in spikelets with 1 floret, prolonged beyond the base of the distal floret in spikelets with 2-6 florets, prolongation hairy, hairs 2-3 mm;

disarticulation above the glumes and beneath the florets.

12-90 mm, with 1 floret;

rachillas not prolonged beyond the base of the floret;

disarticulation above the glumes, beneath the floret.

usually exceeding the floret(s), always longer than 1/4 the length of the adjacent floret, 1-10-veined, narrowly lanceolate to ovate, hyaline or membranous, flexible;

florets usually terete, sometimes laterally or dorsally compressed;

calluses usually well-developed, rounded or blunt to sharply pointed, often antrorsely strigose;

lemmas lanceolate, rectangular, or ovate, membranous to coriaceous or indurate, 3-5-veined, veins inconspicuous, apices entire, bilobed, or bifid, awned, lemma-awn junction usually conspicuous, awns 0.3-30 cm, not branched, usually terminal and centric or eccentric, sometimes subterminal, caducous to persistent, not or once- to twice-geniculate, if geniculate, proximal segment(s) twisted, distal segment straight, flexuous, or curled, not or scarcely twisted;

lodicules 2 or 3;

anthers 1 or 3, sometimes differing in length within a floret;

ovaries glabrous throughout or pubescent distally;

styles 2(3-4)-branched.

much longer than the floret, hyaline to membranous, usually acuminate, 1-3-veined;

florets 3-27 mm, terete to slightly laterally compressed;

calluses (1)1.5-6 mm, sharp or blunt, antrorsely hairy;

lemmas coriaceous to indurate, tan to brown, smooth, glabrous or hairy, hairs sometimes uniformly distributed, sometimes in lines, margins flat, slightly overlapping at maturity, apices awned, lemma-awn junction evident;

awns 50-500 mm, persistent, usually once- or twice-geniculate, sometimes plumose in whole or in part, basal segment often strongly twisted;

paleas from shorter than to subequal to the lemmas, glabrous, 2-veined, not keeled, flat between the veins, apices sometimes scarious, sometimes similar in texture to the body;

lodicules 2 or 3, glabrous or pilose;

anthers 3;

styles 2(3,4), free at the base, if 3 or 4, then 1 or 2 distinctly shorter.

ovoid to fusiform, not beaked, pericarp thin;

hila linear;

embryos less than 1/3 the length of the caryopses.

fusiform, not ribbed, x = 11.

= 7, 8, 10, 11, 12.