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old-pasture blue grass

Bigelow bluegrass, Bigelow's blue grass

Habit Plants perennial; not rhizomatous, not stoloniferous, loosely tufted. Plants usually annual, rarely longer-lived; densely tufted, tuft bases narrow, usually without sterile shoots, not stolonigerous, not rhizomatous.
Culms

20-95 cm tall, 0.8-1.5 mm thick.

(2)5-60(70) cm tall, 0.3-1 mm thick, usually erect, bases rarely geniculate;

nodes terete, usually 1 exserted.

Sheaths

closed for 1/3-2/3 their length;

ligules 0.2-3(4) mm, smooth or sparsely scabrous, truncate to obtuse;

blades 1-3.6 (6) mm wide, flat, thin, lax, veins prominent.

closed for 1/4 - 1/2 their length, usually compressed and keeled, smooth or the keels scabrous;

ligules 2-6 mm, smooth or scabrous, usually decurrent, obtuse to acute;

blades 1.5-5 mm wide, flat, thin, soft, finely scabrous, apices broadly prow-shaped, cauline blades (1)4-15 cm, flag leaf blades usually 1-4 cm.

Basal branching

mainly pseudointravaginal.

intravaginal.

Panicles

4-20(24) cm long, less than 1/4 the plant height, lax;

nodes with 1-3 branches;

branches ascending to spreading, lax, angled, angles prominent, scabrous.

(1)5-15 cm, erect, cylindrical, contracted, sometimes interrupted, congested, with 2-3(5) branches per node;

branches erect or steeply ascending, smooth or sparsely to densely scabrous.

Spikelets

3-5.6 mm, laterally compressed;

florets 2-5;

rachilla internodes glabrous, usually shorter than 1 mm.

4-7 mm, laterally compressed;

florets 3-7;

rachilla internodes to 1 mm, smooth, glabrous.

Glumes

2/3 – 3/4 as long as the adjacent lemmas, distinctly keeled;

lower glumes 1(3)-veined;

upper glumes shorter than or subequal to the lowest lemmas;

calluses webbed;

lemmas 2.4-4 mm, lanceolate to broadly lanceolate, distinctly keeled, usually glabrous, bases of marginal veins rarely sparsely softly puberulent, lateral veins prominent, intercostal regions smooth, minutely bumpy, apices obtuse to sharply acute or acuminate;

palea keels scabrous;

anthers 0.4-1.5 mm.

subequal, distinctly keeled, keels and sometimes the lateral veins scabrous;

lower glumes 1(3)-veined;

upper glumes shorter than or subequal to the lowest lemmas;

calluses webbed;

lemmas 2.6-4.2 mm, lanceolate, distinctly keeled, smooth, keels, marginal veins, and sometimes the lateral veins short- to long-villous, keels hairy to near the apices, marginal veins to 2/3 their length, lateral veins obscure to moderately prominent, intercostal regions glabrous or softly puberulent, upper margins white, apices acute;

palea keels softly puberulent to short-villous at midlength, scabrous near the apices, intercostal regions usually softly puberulent;

anthers 1-3, 0.2-1 mm.

2n

= 28, 28+1.

Poa saltuensis

Poa bigelovii

Distribution
from FNA
CT; IA; IL; IN; KY; MA; MD; ME; MI; MN; NC; NH; NJ; NY; OH; PA; RI; TN; VA; VT; WI; WV; LB; NB; NS; ON; PE; QC
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; NM; NV; OK; TX; UT
[WildflowerSearch map]
[BONAP county map]
Discussion

Poa saltuensis grows in woodlands of the north-central and northeastern United States and adjacent Canada, extending south to Tennessee. The two subspecies are sometimes treated as species. The variation between the two overlaps and is correlated to some extent with ecology and geography. Poa marcida (p. 512), a western species once included in P. saltuensis, differs in having closed sheaths and attenuate lemmas.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Poa bigelovii grows in arid upland regions, particularly on shady, rocky slopes of the southwestern United States and northern Mexico. Plants from southeastern Arizona eastwards are usually glabrous between the lemma veins, whereas more western plants are usually puberulent between the lemma veins. Plants with 1 or 2 small anthers are found in the eastern portion of the species' range; they differ from P. chapmaniana (p. 534) in their persistently contracted panicles and broader leaf blades.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Anthers 0.4-1 mm long; lemma apices obtuse to acute, firm or scarious for up to 0.25 mm
subsp. languida
1. Anthers 0.9-1.5 mm long; lemma apices acute to acuminate, scarious for 0.25-0.5 mm
subsp. saltuensis
Source FNA vol. 24, p. 510. FNA vol. 24, p. 536.
Parent taxa Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Sylvestres Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Homalopoa
Sibling taxa
P. abbreviata, P. alpina, P. alsodes, P. ammophila, P. annua, P. arachnifera, P. arctica, P. arida, P. arnowiae, P. atropurpurea, P. autumnalis, P. bigelovii, P. bolanderi, P. bulbosa, P. chaixii, P. chambersii, P. chapmaniana, P. compressa, P. confinis, P. curtifolia, P. cusickii, P. cuspidata, P. diaboli, P. douglasii, P. eminens, P. fendleriana, P. glauca, P. hartzii, P. howellii, P. infirma, P. interior, P. keckii, P. kelloggii, P. laxa, P. laxa × glauca, P. laxiflora, P. leibergii, P. leptocoma, P. lettermanii, P. macrantha, P. macrocalyx, P. marcida, P. napensis, P. nemoralis, P. nervosa, P. occidentalis, P. paludigena, P. palustris, P. paucispicula, P. piperi, P. porsildii, P. pratensis, P. pringlei, P. pseudoabbreviata, P. reflexa, P. rhizomata, P. secunda, P. sierrae, P. stebbinsii, P. stenantha, P. strictiramea, P. sublanata, P. suksdorfii, P. supina, P. sylvestris, P. tenerrima, P. tracyi, P. trivialis, P. unilateralis, P. wheeleri, P. wolfii, P. ×gaspensis, P. ×limosa, P. ×nematophylla
P. abbreviata, P. alpina, P. alsodes, P. ammophila, P. annua, P. arachnifera, P. arctica, P. arida, P. arnowiae, P. atropurpurea, P. autumnalis, P. bolanderi, P. bulbosa, P. chaixii, P. chambersii, P. chapmaniana, P. compressa, P. confinis, P. curtifolia, P. cusickii, P. cuspidata, P. diaboli, P. douglasii, P. eminens, P. fendleriana, P. glauca, P. hartzii, P. howellii, P. infirma, P. interior, P. keckii, P. kelloggii, P. laxa, P. laxa × glauca, P. laxiflora, P. leibergii, P. leptocoma, P. lettermanii, P. macrantha, P. macrocalyx, P. marcida, P. napensis, P. nemoralis, P. nervosa, P. occidentalis, P. paludigena, P. palustris, P. paucispicula, P. piperi, P. porsildii, P. pratensis, P. pringlei, P. pseudoabbreviata, P. reflexa, P. rhizomata, P. saltuensis, P. secunda, P. sierrae, P. stebbinsii, P. stenantha, P. strictiramea, P. sublanata, P. suksdorfii, P. supina, P. sylvestris, P. tenerrima, P. tracyi, P. trivialis, P. unilateralis, P. wheeleri, P. wolfii, P. ×gaspensis, P. ×limosa, P. ×nematophylla
Subordinate taxa
P. saltuensis subsp. languida, P. saltuensis subsp. saltuensis
Synonyms P. saltuensis var. microlepis, P. languida
Name authority Fernald & Wiegand Vasey & Scribn.
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