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.

20-65 cm, erect or the bases decumbent, not branching above the base, terete or weakly compressed;

nodes terete, 1-2 exserted.

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 1/2-1/3 their length, slightly compressed, keels moderately distinct, smooth or sparsely to moderately scabrous, glabrous, bases of basal sheaths glabrous, distal sheath lengths 1.5-4.4(5.7) times blade lengths;

collars smooth, glabrous;

ligules of cauline leaves 2-8 mm, smooth or scabrous, acute to acuminate, innovation ligules 2-5 mm;

innovation blades to 20 cm, otherwise similar to the cauline blades;

cauline blades gradually reduced in length distally, 1-3.5 mm wide, usually flat or folded, soft, thin, somewhat lax, smooth or sparsely scabrous, primarily over the veins and margins, distinctly keeled, apices narrowly to broadly prow-shaped, flag leaf blades (1.4)3-6(8) cm.

mainly extravaginal.

all or mainly 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.

(2)4-10 cm, nodding, ovoid, sparse, with 20-50 spikelets, proximal internodes usually 1.8-3 cm;

nodes with 1-2(4) branches;

branches 1.5-4.5 cm, ascending to spreading, lax, terete to weakly angled, angles sparsely to moderately scabrous, with 2-7 spikelets.

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

florets 2-5;

rachilla internodes smooth.

(4)6-9(12) mm, lengths to 3.5 times widths, laterally compressed, not sexually dimorphic;

florets 3-8, usually unisexual;

rachilla internodes smooth or sparsely scabrous, usually glabrous, infrequently sparsely puberulent.

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.

3/5 – 4/5 as long as the adjacent lemmas, narrowly lanceolate to lanceolate, distinctly keeled, keels scabrous;

lower glumes 1-3(5)-veined;

calluses webbed, hairs over 1/2 the lemma length;

lemmas 4-6.5 mm, lanceolate, 5-7-veined, distinctly keeled, keels and marginal veins sparsely short- to long-villous, lateral veins moderately prominent, intercostal regions sparsely scabrous, glabrous, margins glabrous, apices acute;

palea keels scabrous;

anthers vestigial (0.1-0.2 mm) or 2.5-4 mm.

= 28.

=28.