Difference between revisions of "Poa laxa"

Haenke
Common names: Lax bluegrass
Treatment appears in FNA Volume 24. Treatment on page 570.
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{{Treatment/ID
 
{{Treatment/ID
 
|accepted_name=Poa laxa
 
|accepted_name=Poa laxa
|accepted_authority=unknown
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|accepted_authority=Haenke
 
|publications=
 
|publications=
 +
|common_names=Lax bluegrass
 
|basionyms=
 
|basionyms=
 
|synonyms=
 
|synonyms=
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|volume=Volume 24
 
|volume=Volume 24
 
|mention_page=
 
|mention_page=
|treatment_page=page 572
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|treatment_page=page 570
 
}}<!--
 
}}<!--
  
--><span class="statement" id="st-undefined" data-properties=""><b>Plants </b>perennial; not or only slightly glaucous; densely tufted, not stoloniferous, not rhizomatous. <b>Basal</b> branching mixed intra- and extra vaginal. <b>Culms</b> 6-18 cm, with 0(1) exserted nodes, upper node in the lower 1/3 of the culms. <b>Sheaths</b> closed for 1/10 – 1/5 their length, terete, smooth or very sparsely scabrous, distal sheath lengths 0.8-1.8 times blade lengths; ligules 1.25-2.5 mm, smooth, apices obtuse, often lacerate; blades thin, sparsely scabrous adaxially, flag leaf blades 1.6-3.8 cm. <b>Panicles</b> 1.5-3.5 cm, slightly lax, ovoid, contracted to loosely contracted, dense to moderately dense, with 2-6 branches per node; branches steeply ascending, fairly straight, sulcate or angled, smooth or infrequently the angles sparsely scabrous, not glaucous. <b>Spikelets</b> laterally compressed; florets 2-5; rachilla internodes smooth, glabrous, lower internodes 0.8-1 mm. <b>Glumes</b> equal, broadly lanceolate, thin; lower glumes 0.75-1.05 mm wide, 3-veined; upper glumes 3.7-4.7 mm long, 0.9-1.3 mm wide, lengths 3.7-4.1 times widths; calluses all glabrous, or some proximal florets within a spikelet sparsely webbed; lemmas 3.7-4.5 mm, broadly lanceolate, distinctly keeled, thin, keels and marginal veins short- to long-villous, hairs extending 1/3-1/2 the keel length, lateral veins usually glabrous, or infrequently sparsely softly puberulent, intercostal regions glabrous; palea keels finely scabrous; anthers 0.8-1.2 mm, poorly formed, sacs not fully maturing, not dehiscing, about 0.1 mm in diameter. <b>2n</b> = ca. 65, 70.</span><!--
+
--><span class="statement" id="st-undefined" data-properties=""><b>Plants </b>perennial; not or only slightly glaucous; densely tufted, not stoloniferous, not rhizomatous. <b>Basal</b> branching mixed, mainly extravaginal or mainly pseudointravaginal, sometimes intravaginal. <b>Culms</b> 8-35 cm tall, 0.5-0.9 mm thick, ascending to erect, slender; nodes terete, 0(1) exserted. <b>Sheaths</b> 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. <b>Panicles</b> 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. <b>Spikelets</b> 4-6 mm, lengths to 3 times widths, laterally compressed; florets 2-5; rachilla internodes shorter than 1 mm, smooth, glabrous. <b>Glumes</b> 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. <b>2n</b> = 28, 42, 84.</span><!--
  
 
-->{{Treatment/Body
 
-->{{Treatment/Body
|discussion=<p><i>Poa laxa</i> × glauca is an eastern low arctic entity which has passed under the name <i>P. flexuosa</i> Sm., <i>P. laxa</i> subsp. flexuosa (Sm.) Hyl., and, more recently, P. laxiuscula (Blytt) Lange. It has also been confused with <i>P. glauca</i> (p. 576). It can be distinguished from <i>P. laxa</i> (see previous) by its more open sheaths and poorly developed, indehiscent anthers. It differs from <i>P. glauca</i> in its broad, thin glumes and lemmas; compact panicles; smooth or nearly smooth, non-glaucous branches; and poorly developed, indehiscent anthers. It also grows in wetter habitats than <i>P. glauca</i>, often around seeps. Its chloroplast DNA is more like that of the American <i>P. laxa </i>subsp.<i> fernaldiana</i> than that of the European subspp. flexuosa and laxa or of <i>P. glauca</i>.</p>
+
|distribution=Maine;N.H.;Colo.;N.Y.;Vt.;Mont.;Oreg.;Wyo.;Alta.;B.C.;Nfld. And Labr.;Que.
 +
|discussion=<p>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).</p><!--
 +
--><p>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.</p>
 
|tables=
 
|tables=
 
|references=
 
|references=
 
}}<!--
 
}}<!--
  
--><!--
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--><div class="treatment-key">
 +
==Key==
 +
<div class="treatment-key-group">
 +
 
 +
{| class="wikitable fna-keytable"
 +
|-id=key-0-1
 +
|1
 +
|Innovations primarily extravaginal; panicle branches fairly straight; calluses glabrous
 +
|[[Poa laxa subsp. banffiana|Poa laxa subsp. banffiana]]
 +
|-id=key-0-1
 +
|1
 +
|Innovations primarily intravaginal; panicle branches flexuous, usually at least some florets having a webbed callus
 +
|[[Poa laxa subsp. fernaldiana|Poa laxa subsp. fernaldiana]]
 +
|}
 +
</div></div><!--
  
 
-->{{#Taxon:
 
-->{{#Taxon:
 
name=Poa laxa
 
name=Poa laxa
 
|author=
 
|author=
|authority=unknown
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|authority=Haenke
 
|rank=species
 
|rank=species
 
|parent rank=section
 
|parent rank=section
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|basionyms=
 
|basionyms=
 
|family=Poaceae
 
|family=Poaceae
 +
|illustrator=Sandy Long
 +
|distribution=Maine;N.H.;Colo.;N.Y.;Vt.;Mont.;Oreg.;Wyo.;Alta.;B.C.;Nfld. And Labr.;Que.
 
|reference=None
 
|reference=None
 
|publication title=
 
|publication title=
 
|publication year=
 
|publication year=
 
|special status=
 
|special status=
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/f6b125a955440c0872999024f038d74684f65921/coarse_grained_fna_xml/V24/V24_799.xml
+
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-data-curation.git/src/314eb390f968962f596ae85f506b4b3db8683b1b/coarse_grained_fna_xml/V24/V24_796.xml
 
|subfamily=Poaceae subfam. Pooideae
 
|subfamily=Poaceae subfam. Pooideae
 
|tribe=Poaceae tribe Poeae
 
|tribe=Poaceae tribe Poeae

Revision as of 17:09, 30 October 2019

Plants perennial; not or only slightly glaucous; densely tufted, not stoloniferous, not rhizomatous. Basal branching mixed, mainly extravaginal or mainly pseudointravaginal, sometimes intravaginal. Culms 8-35 cm tall, 0.5-0.9 mm thick, ascending to erect, slender; nodes terete, 0(1) exserted. Sheaths 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. Panicles 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 mm, lengths to 3 times widths, laterally compressed; florets 2-5; rachilla internodes shorter than 1 mm, smooth, glabrous. Glumes 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, 42, 84.

Distribution

Maine, N.H., Colo., N.Y., Vt., Mont., Oreg., Wyo., Alta., B.C., Nfld. And Labr., Que.

Discussion

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.

Selected References

None.

Key

1 Innovations primarily extravaginal; panicle branches fairly straight; calluses glabrous Poa laxa subsp. banffiana
1 Innovations primarily intravaginal; panicle branches flexuous, usually at least some florets having a webbed callus Poa laxa subsp. fernaldiana