Flora of North America species comparison

20-85 cm, erect, terete or weakly compressed;

nodes terete, 0-1 exserted.

6-18 cm, with 0(1) exserted nodes, upper node in the lower 1/3 of the culms.

closed firmly for 1/7-1/3 their length, sometimes for a longer distance by a hyaline membrane, terete, smooth, glabrous, bases of basal sheaths glabrous;

ligules 1-4 mm, smooth or scabrous;

innovation blades 10-35 cm long, 1-3.5 mm wide;

cauline blades 2-25 cm long, 1.5-4.5 mm wide, flat or folded, lax, both surfaces smooth or sparsely finely scabrous, glabrous, apices narrowly to broadly prow-shaped.

closed for 1/10 – 1/5 their length, terete, smooth or very sparsely scabrous, distal sheath lengths 0.8-1.8 times blade lengths;

ligules 1.25-2.5 mm, smooth, apices obtuse, often lacerate;

blades thin, sparsely scabrous adaxially, flag leaf blades 1.6-3.8 cm.

intra- and extravaginal.

mixed intra- and extra vaginal.

3-12(18) cm, erect, narrowly cylindrical, often interrupted or lobed, congested, with (70)100-200 spikelets;

nodes with (2)3-7(9) branches;

branches 1-3(5) cm, erect to slightly ascending, terete or weakly angled, sparsely to densely coarsely scabrous, with 8-30 spikelets.

1.5-3.5 cm, slightly lax, ovoid, contracted to loosely contracted, dense to moderately dense, with 2-6 branches per node;

branches steeply ascending, fairly straight, sulcate or angled, smooth or infrequently the angles sparsely scabrous, not glaucous.

4-8(10) mm, sexually dimorphic, laterally compressed, pistillate spikelets larger, with fewer florets and more pubescence than the staminate spikelets;

florets 2-10;

rachilla internodes smooth.

laterally compressed;

florets 2-5;

rachilla internodes smooth, glabrous, lower internodes 0.8-1 mm.

unequal, distinctly keeled, keels and lateral veins scabrous;

lower glumes 1-3-veined.

equal, broadly lanceolate, thin;

lower glumes 0.75-1.05 mm wide, 3-veined;

upper glumes 3.7-4.7 mm long, 0.9-1.3 mm wide, lengths 3.7-4.1 times widths;

calluses all glabrous, or some proximal florets within a spikelet sparsely webbed;

lemmas 3.7-4.5 mm, broadly lanceolate, distinctly keeled, thin, keels and marginal veins short- to long-villous, hairs extending 1/3-1/2 the keel length, lateral veins usually glabrous, or infrequently sparsely softly puberulent, intercostal regions glabrous;

palea keels finely scabrous;

anthers 0.8-1.2 mm, poorly formed, sacs not fully maturing, not dehiscing, about 0.1 mm in diameter.

calluses copiously 3-webbed, hairs 4-10 mm, mostly silky, plicate;

lemmas 4.2-6.4 mm, lanceolate, 5-7 veined, distinctly keeled, glabrous, or the keels and marginal veins, sometimes also the lateral veins, densely long-villous, margins glabrous, apices acute;

palea keels scabrous, glabrous or sometimes softly puberulent to long-villous at midlength.

calluses glabrous or sparsely dorsally webbed, hairs plicate, rarely with additional webs under the marginal veins;

lemmas 3.5-5 mm, lanceolate, distinctly keeled, keels and marginal veins sparsely short- to long-villous, margins glabrous, apices acute;

palea keels scabrous, glabrous or softly puberulent to long-villous at midlength;

anthers vestigial (0.1-0.2 mm) or 1.6-2.7 mm.

= 42, ca. 54, 56, ca. 63, 84.

= ca. 65, 70.