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narrow-flower bluegrass, northern bluegrass

Photo is of parent taxon

narrow-flower blue grass, northern bluegrass

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

20-60(100) cm, bases decumbent or sometimes erect, terete, with 1-2 exserted nodes.

Sheaths

closed for 1/10 – 1/5(1/4) their length, terete, bases of basal sheaths glabrous;

ligules 2-5 mm, milky white, smooth or sparsely scabrous, acute to acuminate;

innovation blades similar in texture and shape to the cauline blades;

cauline blades not greatly reduced upwards, 1.5-4(5) mm wide, flat or folded, thin, lax, smooth or sparsely scabrous, apices narrowly prow-shaped.

Basal branching

mostly extravaginal, some intravaginal.

Panicles

5-18(25) cm, lax, loosely contracted to open, sparse, with 20-65 spikelets and usually 2(7) branches per node;

branches 3-15 cm, ascending to spreading, angled, angles finely to coarsely, sparsely to fairly densely scabrous, infrequently smooth, with 3-10(15) spikelets in the distal 1/2.

Spikelets

6-10 mm, lengths 3-3.6 times widths, lanceolate to narrowly ovate, laterally compressed, sometimes bulbiferous, drab, often slightly glaucous;

florets 3-4(7), normal or bulb-forming;

rachilla internodes 1.2-2 mm, slightly dorsally compressed, smooth or sparsely muriculate.

not bulbiferous;

florets normal.

Glumes

subequal, lanceolate to broadly lanceolate, dull, frequently glaucous, obtuse to acute;

lower glumes 3-veined;

upper glumes (3.7)4.1-6.5 mm;

calluses usually crowned with 0.2-2 mm hairs, sometimes glabrous;

lemmas 4-6 mm, lanceolate, distinctly compressed, distinctly keeled, keels, marginal veins, and sometimes the lateral veins short- to long-villous, hairs extending for 3/4 of the keel, intercostal regions glabrous, sparsely puberulent or hispidulous proximally, usually sparsely to moderately densely scabrous distally, hairs distinctly shorter than those of the keel and veins, margins weakly inrolled, broadly scarious, glabrous, apices acute;

palea keels scabrous, often softly puberulent at midlength, intercostal regions glabrous or puberulent;

anthers 1.2-2 mm, sometimes aborted late in development or undeveloped.

Anthers

1.2-2 mm.

2n

= 42, [81, 84, 86?].

Poa stenantha

Poa stenantha var. stenantha

Distribution
from FNA
AK; CO; ID; MT; OR; UT; WA; AB; BC
[WildflowerSearch map]
[BONAP county map]
[BONAP county map]
Discussion

Poa stenantha grows in coastal meadows and on cliffs in subarctic and boreal forests; it is less common in moist, more southern subalpine and low alpine meadows and thickets. Its range extends from western Alaska to the northern Cascades and Rocky Mountains and, as a disjunct, to Patagonia. Poa stenantha was originally described as growing in Kamchatka, Russia, but the Russian plants have since been referred to other species.

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

Poa stenantha var. stenantha can be difficult to separate from P. secunda subsp. secunda (p. 588). Its main distinguishing features are its strongly keeled lemmas with glabrous intercostal regions, and, when present, callus hairs longer than 0.2 mm. Plants with large panicles and glabrous calluses have been called P. macroclada Rydb. Such plants grow infrequently in the U.S. Rocky Mountain portion of the species' range. They intergrade with the more compact typical form.

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

Key
1. Spikelets not bulbiferous
var. stenantha
1. Spikelets bulbiferous
var. vivipara
Source FNA vol. 24, p. 592. FNA vol. 24, p. 594.
Parent taxa Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Secundae > subsect. Halophytae Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Secundae > subsect. Halophytae > Poa stenantha
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. 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. stenantha var. vivipara
Subordinate taxa
P. stenantha var. stenantha, P. stenantha var. vivipara
Synonyms P. macroclada
Name authority Trin. unknown
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