Flora of North America species comparison

15-60 cm, erect or the bases decumbent, not branching above the base, 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 for about 1/2 their length, slightly compressed, distinctly keeled, glabrous, bases of basal sheaths glabrous, distal sheath lengths 4-60 times blade lengths;

collars of proximal leaves usually retrorsely scabrous or pubescent distally and about the throat;

ligules 0.5-4 mm, smooth or scabrous, apices truncate to acute;

innovation blades similar to the cauline blades;

cauline blades 1-4 mm wide, usually flat, sometimes slightly folded, smooth or sparsely scabrous, primarily over the veins, apices broadly prow-shaped, blades steeply reduced in length distally, flag leaf blades 0.2-3(6) cm.

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.

mainly extravaginal.

mixed intra- and extra vaginal.

5-15 cm, erect or lax, pyramidal, open, sparse, with 20-80 spikelets, proximal internodes usually 3+ cm;

nodes usually with 2 branches;

branches (2)3-7(10) cm, spreading to reflexed, straight, angled, angles scabrous, with 2-8(10) 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.

5-8 mm, lengths to 3.5 times widths, laterally compressed, not sexually dimorphic;

florets 2-5;

rachilla internodes smooth.

laterally compressed;

florets 2-5;

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

narrowly lanceolate to lanceolate, distinctly keeled;

lower glumes 1-3-veined;

calluses webbed, hairs over 1/3 the lemma length;

lemmas 3-6 mm, lanceolate, distinctly keeled, keels and marginal veins sparsely short- to long-villous, lateral veins moderately prominent, intercostal regions glabrous or the upper florets in the spikelets softly puberulent, margins glabrous, apices acute;

palea keels scabrous, softly puberulent at midlength;

anthers vestigial (0.1-0.2 mm) or 2-3.5 mm.

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.

= 28.

= ca. 65, 70.