Flora of North America species comparison

20-150 cm tall, 2-4 mm thick, erect or spreading, sometimes decumbent and rooting from the lower nodes, distal portion sometimes floating in shallow water.

annual, not woody, not branching above the base;

internodes hollow.

glabrous, keeled;

ligules 5-15 mm;

blades 5-25 cm long, 3-10 mm wide, both surfaces smooth.

closed for their whole length or almost so;

collars without tufts of hair on the sides;

auricles sometimes present;

ligules hyaline, glabrous, often lacerate, occasionally ciliate, those of the lower and upper cauline leaves usually similar;

pseudopetioles absent;

blades linear to narrowly lanceolate, venation parallel, cross venation sometimes evident;

cross sections non-Kranz, without arm or fusoid cells;

epidermes without microhairs, sometimes papillate.

10-50 cm long, 2-3 cm wide;

branches 3-5 cm, paired or solitary, usually appressed to ascending, divergent at anthesis, with 1-4 spikelets;

pedicels 0.8-20 mm.

terminal panicles or racemes;

disarticulation above the glumes and beneath the florets or below the glumes.

(15)18-39 mm long, 1.7-3.3 mm wide, cylindrical and terete, except slightly laterally compressed at anthesis, rectangular in side view, with 8-16 florets.

2.5-60 mm, not viviparous, slightly to strongly laterally compressed, with 1-30 florets, proximal florets bisexual, distal 1-3 florets usually sterile, sometimes pistillate, sometimes reduced and amalgamated into a knob- or club-shaped rudiment;

rachillas prolonged beyond the base of the distal floret.

exceeded by the distal florets, shorter than to longer than the adjacent lemmas, mostly membranous, scarious distally, 1-11-veined, apices usually rounded to acute;

florets laterally or dorsally compressed;

calluses blunt, glabrous or with hairs;

lemmas of sexual florets rectangular or ovate, mostly membranous, scarious distally, often with a purplish band adjacent to the scarious apices, (4)5-15-veined, veins not converging distally, often prominent, unawned or awned, awns not branched, apices entire to bilobed or bifid, awns straight, subterminal or from the sinuses;

paleas from shorter than to longer than the lemmas, similar in texture, 2-veined, veins keeled, sometimes winged;

lodicules 2, fleshy, usually connate into a single structure, without a membranous wing, truncate, not ciliate, not or scarcely veined;

anthers 1, 2, or 3;

ovaries glabrous;

styles 2-branched, bases persistent, branches plumose distally.

1.3-3.9 mm;

upper glumes 2.7-5 mm;

rachilla internodes 1.9-2.5 mm;

lemmas 5.2-8 mm, midveins extending to within 0.1 mm of the apical margins, scabrous over and between the veins, prickles about 0.05 mm, apices acute, usually entire;

paleas from shorter than to 0.6(1.5) mm longer than the lemmas, keels winged, apices bifid, teeth 0.1-0.4 mm, parallel to convergent, sometimes crossing when dry;

anthers 1.5-3 mm, usually purple.

2-3 mm.

ovoid to ellipsoid, longitudinally grooved or not;

hila usually linear;

embryos less than 1/3 as long as the caryopses.

= (8)9, 10.

= 40.