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Howell's blue grass

Hartz's bluegrass

Habit Plants usually annual, rarely longer-lived; densely tufted, tuft bases narrow; not stoloniferous, not rhizomatous. Plants perennial; not glaucous; densely to loosely tufted, not rhizomatous,occasionally weakly stoloniferous.
Culms

(10) 25-80(120) cm tall, 0.4-1.75 mm thick, usually erect;

nodes terete, usually 1-2 exserted.

10-33(45) cm, usually decumbent, terete;

nodes terete, 0(1) exserted.

Sheaths

closed for 1/2 - 7/8 their length, usually weakly compressed and keeled, usually scabrous, rarely smooth;

ligules 1.5-5(10) mm, smooth or scabrous, acute;

blades 1-7(10) mm wide, flat, lax, soft, finely scabrous, apices narrowly prow-shaped, cauline blades 2-10 cm.

closed for 1/7 – 1/5(1/3) their length, terete, usually lustrous, bases of basal sheaths glabrous;

ligules (1.5)2-7 mm, smooth or sparsely scabrous, margins usually decurrent, apices obtuse to acuminate;

innovation blades similar in texture and shape to those of the culms;

cauline blades 2-9 cm, gradually increasing or decreasing in length upwards, 1.5-3 mm wide, folded to involute, moderately thick, soft, abaxial surfaces smooth, adaxial surfaces smooth or somewhat scabrous, usually glabrous, infrequently sparsely hispidulous, apices narrowly prow-shaped.

Basal branching

intravaginal.

extra- and intravaginal.

Panicles

10-25(30) cm, erect, eventually open, with (1)3-5(7) branches per node;

branches eventually spreading or reflexed, fairly straight, angled, angles usually moderately to densely scabrous, rarely sparsely scabrous.

2.5-6(12) cm, erect, narrowly lanceolate, contracted or narrowly ovate in some bulbiferous plants, moderately congested, with 7-40 spikelets;

nodes with (1)2(4) branches;

branches 1-3 cm, erect to ascending, straight, sulcate, smooth or sparsely to moderately scabrous, with 1-10 spikelets in the distal 1/3 – 2/3.

Spikelets

(2)4-6 mm, laterally compressed, with 2-5 florets;

rachilla internodes about 1 mm, smooth, usually softly puberulent, infrequently glabrous.

4.8-7.4 mm, lengths 3.5-4 times widths, lanceolate, weakly laterally compressed, sometimes bulbiferous, lustrous;

florets (2)3-5(6), normal or bulb-forming;

rachilla internodes 0.8-2 mm, smooth, sometimes sparsely hispidulous.

Glumes

slightly unequal, lanceolate, distinctly keeled, keels and sometimes the lateral veins sparsely to moderately scabrous;

lower glumes 1-3-veined;

upper glumes shorter than or subequal to the lowest lemmas;

calluses of some or all florets sparsely webbed;

lemmas 2.5-3.5 mm, lanceolate to narrowly lanceolate, distinctly keeled, crisply puberulent proximally, hairs evenly distributed, finely scabrous distally, lateral veins obscure to prominent, margins narrowly hyaline, glabrous, apices narrowly acute, infrequently anthocyanic;

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

anthers 3, 0.2-1 mm.

mostly broadly scarious, somewhat lustrous, keels indistinct, smooth or sparsely scabrous distally;

lower glumes 3-veined;

upper glumes frequently exceeding the lowest lemmas;

calluses glabrous or with a crown of hairs, hairs to 2 mm;

lemmas (3.3)3.5-7 mm, lanceolate, usually weakly keeled, more or less evenly and somewhat loosely to densely hairy over the proximal 1/3-1/2, hairs usually longer than 0.5 mm, sparsely scabrous in the middle 1/3, smooth distally, lateral veins obscure, margins weakly inrolled, broadly scarious, glabrous, apices long-scarious, acute to shortly obtuse, often erose, often bronze-colored below the apices;

palea keels sparsely scabrous, softly puberulent at midlength, intercostal regions softly puberulent;

anthers usually all aborted late in development and 0.8-1.8 mm, infrequently well developed and 2-2.8 mm.

2n

= unknown.

= 63, 70.

Poa howellii

Poa hartzii

Distribution
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; NT; NU; QC; Greenland
[BONAP county map]
Discussion

Poa howellii grows primarily on rocky banks and wooded slopes, from the coastal ranges of southern British Columbia to southern California. It differs from P. bolanderi (see above) in having puberulent, rather than smooth or scabrous, lemmas, and in growing at lower elevations, mostly from near sea level to 1000 m.

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

Poa hartzii grows only in the high arctic. It generally grows on open ground, on sandy or clayey soils, or on slumping slopes of old marine terraces. It carries two chloroplast genomes within its populations; one of these links it to P. secunda (p. 586) and P. ammophila (see next), the other to P. glauca (p. 576). Morphologically, it is closest to P. secunda and P. ammophila.

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

Key
1. Spikelets bulbiferous
subsp. vrangelica
1. Spikelets not bulbiferous.
→ 2
2. Lemmas 5.5-7 mm long; anthers well developed, 2-2.8 mm long
subsp. alaskana
2. Lemmas 3.3-5.4 mm long; anthers usually aborted and shorter than 1.5 mm
subsp. hartzii
Source FNA vol. 24, p. 534. FNA vol. 24, p. 589.
Parent taxa Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Homalopoa Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Secundae > subsect. Secundae
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. 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
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. 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. hartzii subsp. alaskana, P. hartzii subsp. hartzii, P. hartzii subsp. vrangelica
Synonyms P. bolanderi var. howellii
Name authority Vasey & Scribn. Gand.
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