Flora of North America species comparison

20-80 (100) cm tall, (1.5)2-3.5 mm thick, not or only slightly spongy, sometimes rooting at the lower nodes.

annual, not woody, not branching above the base;

internodes hollow.

smooth to scabridulous, keeled, sometimes weakly so;

ligules 1-4 mm, usually rounded, sometimes acute to mucronate, erose-lacerate;

blades 12-30 cm long, 2-6 mm wide, abaxial surfaces smooth or scabridulous, adaxial surfaces scabridulous to scabrous.

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.

6-25 cm long, 2.5-21 cm wide, pyramidal, open, nodding;

branches 5-13 cm, straight to lax, lower branches usually strongly divergent to drooping at maturity, sometimes ascending, with 15-50 spikelets, these often confined to the distal 2/3;

pedicels 0.5-7 mm.

terminal panicles or racemes;

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

1.8-4 mm long, 1.2-2.9 mm wide, laterally compressed, oval in side view, with 3-7 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.

ovate, 1-1.5 times longer than wide, narrowing from midlength or above, veins terminating below the apical margins, apices often splitting with age;

lower glumes 0.5-1.2 mm, rounded to obtuse;

upper glumes 0.6-1.2 mm, acute or rounded;

rachilla internodes 0.1-0.6 mm;

lemmas 1.2-2 mm, ovate in dorsal view, veins raised, scabridulous over and between the veins, apices acute, prow-shaped;

paleas slightly shorter than to equaling the lemmas, lengths 1.5-3 times widths, keeled, keels not winged, tips pointing towards each other, apices narrowly notched between the keels;

anthers 2, (0.2)0.4-0.6 mm, purple or yellow.

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.

0.5-2 mm.

ovoid to ellipsoid, longitudinally grooved or not;

hila usually linear;

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

= (8)9, 10.

= 20 [reports of 28 are questionable].