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Wolf's bluegrass

banff bluegrass, glaucous bluegrass, lax bluegrass, Mt. Washington bluegrass, wavy blue grass

Habit Plants perennial; not rhizomatous, not stoloniferous, loosely tufted. Plants perennial; not or only slightly glaucous; densely tufted, not stoloniferous, not rhizomatous.
Culms

25-90 cm.

8-35 cm tall, 0.5-0.9 mm thick, ascending to erect, slender;

nodes terete, 0(1) exserted.

Sheaths

closed for 1/2 - 3/4 their length, smooth or sparsely scabrous, margins not ciliate;

ligules 0.3-2.1 mm, smooth or sparsely scabrous, truncate to obtuse, ciliolate;

blades 0.6-3.5 mm wide, flat.

closed for 1/5-1/3 their length, terete, smooth, glabrous, bases of basal sheaths glabrous;

collars smooth or scabrous, glabrous;

ligules 2-4 mm, smooth, apices acute, often lacerate;

innovation blades similar to the cauline blades;

cauline blades 1-2(3) mm wide, flat, thin, soft, smooth, narrowly prow-tipped, blades not strongly graduated or reduced upwards.

Basal branching

mainly pseudointravaginal.

mixed, mainly extravaginal or mainly pseudointravaginal, sometimes intravaginal.

Panicles

7.5-15(18) cm, lax, pyramidal, open, sparse;

nodes with 1-3(5) branches;

branches 3-8 cm, ascending, straight to spreading, angled, angles prominent, scabrous.

2-8 cm, slightly lax, usually loosely contracted and sparse, infrequently contracted and dense;

nodes with 1-3(5) branches;

branches 1-3(4) cm, usually ascending or weakly spreading, infrequently erect, fairly straight or flexuous, slender, sulcate or angled, smooth or the angles sparsely scabrous, with 1-8 spikelets.

Spikelets

4-6.5 mm, laterally compressed;

florets 2-5;

rachilla internodes to 1 mm, smooth, glabrous.

4-6 mm, lengths to 3 times widths, laterally compressed;

florets 2-5;

rachilla internodes shorter than 1 mm, smooth, glabrous.

Glumes

1/2-1/3 the length of the adjacent lemmas, distinctly keeled, keels scabrous;

lower glumes subulate to narrowly lanceolate, (1)3-veined;

upper glumes shorter than or subequal to the lowest lemmas;

calluses webbed;

lemmas (2.5)3.2-4.7 mm, lanceolate, green, distinctly keeled, keels and marginal veins long-villous, hairs extending up almost the whole keel length, lateral veins prominent, intercostal regions smooth, minutely bumpy, usually glabrous, rarely sparsely softly puberulent, apices acute, blunt, or pointed, white, not bronze;

palea keels softly puberulent at midlength, apices scabrous;

anthers (0.5)0.8-1.2(1.5) mm.

nearly equaling or slightly longer than the adjacent lemmas, lanceolate to broadly lanceolate, thin, distinctly keeled, keels smooth or sparsely scabrous;

lower glumes 1-3-veined;

upper glumes shorter than or subequal to the lowest lemmas;

calluses glabrous or webbed, hairs usually shorter than 1/4 the lemma length, sparse;

lemmas 3-4.6 mm, lanceolate to broadly lanceolate, thin, distinctly keeled, keels and marginal veins short- to long-villous, lateral veins glabrous or sparsely softly puberulent, lateral veins obscure, intercostal regions glabrous, margins glabrous, apices acute;

paleas sparsely scabrous over the keels;

anthers (0.6)0.8-1.1(1.3) mm.

2n

= 28.

= 28, 42, 84.

Poa wolfii

Poa laxa

Distribution
from FNA
AR; IA; IL; IN; MN; MO; OH; VA; WI
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; ME; MT; NH; NY; OR; VT; WY; AB; BC; NL; QC
[BONAP county map]
Discussion

Poa wolfii is an uncommon species that grows in boggy areas of eastern deciduous forests, primarily west of the Appalachian divide. It differs from P. sylvestris (p. 512) in having fewer branches, larger spikelets, and lemmas that are usually glabrous between the veins.

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

Poa laxa is a low arctic to high alpine amphiatlantic species. It has been treated as a series of separate species, but the differences seem relatively minor and incomplete. Its short anthers and smoother branches usually distinguish it from P. glauca (p. 576), with which it can hybridize to form P. laxa x glauca (p. 572).

Poa laxa has four subspecies, two of which are native to the Flora region; subsp. laxa grows in central Europe; and subsp. flexuosa (Sm.) Hyl. in northwestern Europe.

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

Key
1. Innovations primarily extravaginal; panicle branches fairly straight; calluses glabrous
subsp. banffiana
1. Innovations primarily intravaginal; panicle branches flexuous, usually at least some florets having a webbed callus
subsp. fernaldiana
Source FNA vol. 24, p. 514. FNA vol. 24, p. 570.
Parent taxa Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Sylvestres Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Oreinos
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. 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. ×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. 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 × 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. laxa subsp. banffiana, P. laxa subsp. fernaldiana
Name authority Scribn. Haenke
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