Flora of North America species comparison

30-120 cm, bases often decumbent.

35-80 cm, erect or the bases decumbent, terete or weakly compressed;

nodes terete, 1-2 exserted.

closed for (1/20) 1/2-7/8 their length, terete, throats frequently ciliate near the point of fusion;

ligules 0.5-2.7 mm, smooth or sparsely scabrous, truncate to obtuse;

blades 0.7-5 mm wide, flat, thin, lax.

closed for 1/3-1/4 their length, terete to slightly compressed, at least some proximal sheaths densely retrorsely scabrous, hispidulous, or softly puberulent for the upper 1/4 of their length, bases of basal sheaths glabrous, distal sheath lengths (1.4)1.7-4.6(6.2) times blade lengths;

collars of proximal leaves glabrous or with hairs the same length as those of their sheaths;

ligules 0.5-2 mm, smooth or scabrous, sometimes puberulent, truncate, those of the lower culm and innovation leaves 0.5-1.5 mm, abaxial surfaces scabrous to softly puberulent, truncate;

innovation blades folded or involute, infrequently flat, moderately thick, soft, adaxial surfaces usually densely scabrous to hispidulous;

cauline blades 2-3.5 mm wide, flat or folded, smooth or sparsely scabrous, glabrous or hispidulous, apices narrowly to broadly prow-shaped, blades gradually reduced distally or the middle blades longest, flag leaf blades 1-10 cm long.

mainly pseudointravaginal.

mainly extra-vaginal.

(6.7)9-20 cm, open, narrowly conical at maturity;

nodes with (2)3-10 branches per node;

branches (2)3-7 cm, spreading to eventually reflexed, straight, angled, angles several, densely scabrous, with 1-11 spikelets.

5-12(18) cm, erect or nodding, ovoid to pyramidal, loosely contracted to open, with 20-70 spikelets, proximal internodes usually shorter than 3.5 cm;

nodes with 2-5 branches;

branches (1)1.7-6.5 cm, ascending to spreading or reflexed, lax, terete or weakly angled, sparsely to moderately scabrous, with 2-8(12) spikelets.

2.5-4.4 mm, laterally compressed;

florets 2-3(4);

rachilla internodes longer than (1)1.2 mm, smooth, glabrous.

5.5-10 mm, lengths to 3.5 times widths, laterally compressed, not sexually dimorphic;

florets 2-7;

rachilla internodes smooth or scabrous, glabrous or sparsely to densely hispidulous.

distinctly keeled, keels scabrous;

lower glumes 1(3)-veined;

upper glumes shorter than or subequal to the lowest lemmas;

calluses webbed;

lemmas 2.1-3.1 mm, broadly lanceolate, distinctly keeled, keels and marginal veins short-villous, extending to near the apices on the keels, lateral veins prominent, softly puberulent to short-villous, intercostal regions usually sparsely softly puberulent, smooth, apices obtuse to acute;

palea keels softly puberulent at midlength, apices finely scabrous;

anthers 1-1.8 mm.

1/4 - 2/3(3/4) as long as the adjacent lemmas, lanceolate, distinctly keeled;

lower glumes 1-3-veined, 1/4-1/2 as long as the adjacent lemmas;

calluses glabrous;

lemmas 3-6 mm, lanceolate, distinctly keeled, keels and marginal veins glabrous or softly puberulent to short-villous, intercostal regions glabrous or hispidulous, infrequently puberulent, smooth or finely scabrous, lateral veins obscure to moderately prominent, margins glabrous, apices acute;

palea keels scabrous, intercostal regions glabrous;

anthers usually vestigial (0.1-0.2 mm) or aborted late in development and up to 2 mm, rarely normal.

= 28.

= 56, 61, 62, 63, 64, 66, 61, 70, ca. 74, 75, 79, 80, 81, 87, 89, 90, 91.