Poa stenantha
Poa occidentalis
narrow-flower bluegrass, northern bluegrass
New Mexican bluegrass, New Mexico bluegrass
20-60(100) cm, bases decumbent or sometimes erect, terete, with 1-2 exserted nodes.
20-110 cm.
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.
closed for (1/5)1/4 – 1/2(3/5) their length, distinctly compressed and keeled, usually densely retrorsely scabrous, rarely sparsely scabrous, margins not ciliate;
ligules 3-12 mm, densely scabrous, acute to acuminate;
blades (1.2)1.5-6(10) mm wide, flat, lax, apices broadly prow-shaped.
mostly extravaginal, some intravaginal.
mixed intra- and extra-vaginal.
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.
(6)12-40 cm, lax, eventually open, spikelets numerous, with 2-7 branches per node;
branches (3)5-18(23) cm, eventually spreading or drooping, angled, angles densely scabrous, with (5)8-40(120) 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.
(3)4-7(8) mm, laterally compressed, with 3-7 florets;
rachilla internodes shorter than 1 mm, smooth.
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.
distinctly keeled, keels scabrous;
lower glumes 2-3.5 mm, 1-veined;
upper glumes 2.5-4.2 mm, shorter than or subequal to the lowest lemmas;
calluses webbed;
lemmas 2.6-4.2 mm, narrowly lanceolate, distinctly keeled, scabrous distally, keels and marginal veins short- to long-villous, keel hairs extending to midlength, marginal vein hairs to 1/3 the lemma length, lateral veins and intercostal regions usually sparsely softly puberulent, lateral veins prominent, apices narrowly acute;
palea keels scabrous, glabrous;
anthers 0.3-1 mm.
= 42, [81, 84, 86?].
= 14, 28.
Poa stenantha
Poa occidentalis
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 occidentalis grows in natural openings and disturbed sites in mixed coniferous forests of the southwestern United States. It is one of the three diploid species of Poa known to be native to North America. The tetraploid count was obtained from a single giant individual. Poa occidentalis has been confused with P. tracyi (p. 543), but P. occidentalis consistently has shorter, well-developed anthers and lacks rhizomes. It also usually has longer ligules relative to the blade width, and is shorter-lived. A few plants are intermediate in some characteristics. Small plants of P. occidentalis sometimes resemble P. reflexa (see next).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Spikelets not bulbiferous | var. stenantha |
1. Spikelets bulbiferous | var. vivipara |
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