View source for Polytrichum jensenii

{{Treatment/ID
|accepted_name=Polytrichum jensenii
|accepted_authority=I. Hagen
|publications={{Treatment/Publication
|title=Meddel. Grønland
|place=15: 444. 1897,
}}
|basionyms=
|synonyms={{Treatment/ID/Synonym
|name=Polytrichum commune var. jensenii
|authority=(I. Hagen) Mönkemeyer
|rank=variety
}} {{Treatment/ID/Synonym
|name=Polytrichum commune var. diminutum
|authority=(I. Hagen) D. G. Long
|rank=variety
}} {{Treatment/ID/Synonym
|name=Polytrichum commune var. yukonense
|authority=(Cardot & Thériot) Frye
|rank=variety
}} {{Treatment/ID/Synonym
|name=Polytrichum yukonense
|authority=
|rank=species
}}
|hierarchy=Polytrichaceae;Polytrichum;Polytrichum jensenii
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Polytrichaceae]]</div><div class="higher-taxon"><small>genus</small>[[Polytrichum]]</div><div class="higher-taxon"><small>species</small>[[Polytrichum jensenii]]</div></div>
|volume=Volume 27
|mention_page=page 134
|treatment_page=page 137
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Plants </b>rather fragile, forming extensive green carpets or as scattered stems among other bryophytes. <b>Stems</b> 3–12 cm. <b>Leaves</b> (4–)6–10 mm, ± distant, not crowded; closely appressed, straight or erect-spreading and weakly flexuose when dry, erect-spreading to widely spreading or weakly recurved when moist, caducous at the base of blade; sheath short, scarcely broadened and rather weakly differentiated; marginal lamina narrow, 2–3 cells wide, erect to somewhat involute towards the apex, entire to finely and obscurely serrulate from the middle upwards, the teeth rather weak and distant; costa smooth abaxially, ending in a short, weakly toothed tip; lamellae crenulate in profile, 8–12 cells high, with paired, projecting knobs along the margins, the marginal cells in section rather narrow, retuse, thick-walled, brownish, smooth; sheath cells rather short rectangular, 60–90 × 15–22 µm; cells of the marginal lamina ± isodiametric; perichaetial leaves with sheathing bases usually hidden by upper stem leaves. <b>Seta</b> 1.5–4.5 cm, brownish. <b>Capsule</b> 2.5–3.5 mm, sharply 4–5-angled, short rectangular to cubic.</span><!--

-->{{Treatment/Body
|habitat=Periodically flooded areas, bogs, sedge meadows, margins of lakes, streams and rivers
|elevation=low to moderate elevations (to 1500 m)
|distribution=Greenland;Nfld. and Labr. (Labr.);N.W.T.;Nunavut;Que.;Yukon;Alaska;Wyo.;Arctic Europe;Asia (n Russia).
|discussion=<p><i>Polytrichum jensenii</i> is a widely distributed plant of the high Arctic, with a sporadic disjunct occurrence southward, where its distribution is poorly documented. In Nunavut, it is known from Melville Island. In arctic America it replaces <i>P. commune</i> north of the tree line (D. G. Long 1985, as <i>P. commune</i> var. diminutum), and is notable for its rather fragile texture, entire to weakly toothed leaf margins, and caducous leaf blades. The marginal cells of the lamellae are similar to those of <i>P. commune</i>. Forms of <i>P. swartzii</i> have entire or nearly entire, caducous leaves, but the marginal cells of the lamellae are rounded quadrate and thin-walled, absent the distinctive, thickened knobs of <i>P. jensenii</i> and <i>P. commune</i>. Genetic evidence may support the recognition of <i>P. jensenii</i> as a distinct species (G. S. Derda and R. Wyatt 1999).</p>
|tables=
|references=
}}<!--

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-->{{#Taxon:
name=Polytrichum jensenii
|authority=I. Hagen
|rank=species
|parent rank=genus
|synonyms=Polytrichum commune var. jensenii;Polytrichum commune var. diminutum;Polytrichum commune var. yukonense;Polytrichum yukonense
|basionyms=
|family=Polytrichaceae
|habitat=Periodically flooded areas, bogs, sedge meadows, margins of lakes, streams and rivers
|elevation=low to moderate elevations (to 1500 m)
|distribution=Greenland;Nfld. and Labr. (Labr.);N.W.T.;Nunavut;Que.;Yukon;Alaska;Wyo.;Arctic Europe;Asia (n Russia).
|reference=None
|publication title=Meddel. Grønland
|publication year=
|special status=
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/f50eec43f223ca0e34566be0b046453a0960e173/coarse_grained_fna_xml/V27/V27_167.xml
|genus=Polytrichum
|species=Polytrichum jensenii
}}<!--

-->[[Category:Treatment]][[Category:Polytrichum]]