View source for Eleocharis tenuis

{{Treatment/ID
|accepted_name=Eleocharis tenuis
|accepted_authority=(Willdenow) Schultes
|publications={{Treatment/Publication
|title=Mant.
|place=2: 89. 1824
|year=1824
}}
|common_names=Slender spike-rush;dog’s hair
|special_status={{Treatment/ID/Special_status
|code=F
|label=Illustrated
}}{{Treatment/ID/Special_status
|code=E
|label=Endemic
}}
|basionyms={{Treatment/ID/Basionym
|name=Scirpus tenuis
|authority=Willdenow
|rank=species
|publication_title=Enum. Pl.
|publication_place=1: 76. 1809
}}
|synonyms=
|hierarchy=Cyperaceae;Eleocharis;Eleocharis subg. Eleocharis;Eleocharis sect. Eleocharis;Eleocharis (sect. Eleocharis) ser. Eleocharis;Eleocharis tenuis
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Cyperaceae]]</div><div class="higher-taxon"><small>genus</small>[[Eleocharis]]</div><div class="higher-taxon"><small>subgenus</small>[[Eleocharis subg. Eleocharis]]</div><div class="higher-taxon"><small>section</small>[[Eleocharis sect. Eleocharis]]</div><div class="higher-taxon"><small>series</small>[[Eleocharis (sect. Eleocharis) ser. Eleocharis]]</div><div class="higher-taxon"><small>species</small>[[Eleocharis tenuis]]</div></div>
|volume=Volume 23
|mention_page=page 61, 65, 66, 67, 69, 85, 87, 88
|treatment_page=page 86
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Plants </b>perennial, mat-forming; rhizomes evident, 0.4–2 mm thick, soft to hard, cortex persistent, longer internodes 2–10 mm, scales persistent or decaying to fibers, 5–10 mm, papery, finely to coarsely fibrous. <b>Culms</b> terete or usually with 4 or 5(–6) angles, often sulcate; 5–90 cm × 0.2–0.5(–0.8) mm, firm to soft. <b>Leaves</b>: distal leaf sheaths persistent, not splitting, proximally dark red (or yellow-brown), distally green or stramineous or red, membranous, apex often reddish, obtuse to acute, often callose, often with tooth to 0.2(–0.9) mm. <b>Spikelets</b> ovoid, 3–6 × 1.5–2 mm, apex obtuse to acute; proximal scale amplexicaulous, apex entire; subproximal scale with flower; floral scales appressed in fruit, 20–60, 5–6 per mm of rachilla, medium to dark brown, midrib region often paler, ovate, 1.5–2.5 × 1 mm, apex rounded (to acute), entire, rarely shallowly notched, carinate in distal part of spikelet. <b>Flowers</b>: perianth bristles absent or sometimes 1–3, stramineous to pale brown, slender, to equaling achene, obscurely retrorsely spinulose; stamens 3; anthers brown, 0.8–1.8 mm; styles 3-fid. <b>Achenes</b> falling with or before scales, lemon yellow, dark yellow, medium brown, or green, obpyriform, trigonous, angles evident, sometimes prominent, 0.6–0.9 × 0.45–0.7 mm, finely to coarsely rugulose and usually alveolate (cancellate) at 10–20X, 6–10(–14) sharp horizontal ridges in each vertical series. <b>Tubercles</b> brown, pyramidal and to as high as wide to greatly depressed-apiculate, often rudimentary, 0.05–0.3 × 0.25–0.4 mm.</span><!--

-->{{Treatment/Body
|distribution=N.B.;N.S.;P.E.I.;Que.;Ala.;Ark.;Calif.;Conn.;D.C.;Del.;Ga.;Ill.;Ind.;Iowa;Kans.;Ky.;La.;Maine;Mass.;Md.;Miss.;Mo.;N.C.;N.H.;N.J.;N.Y.;Nebr.;Ohio;Okla.;Pa.;R.I.;S.C.;S.Dak.;Tenn.;Tex.;Va.;Vt.;W.Va.;Wis.
|discussion=<p>Varieties 3 (3 in the flora).</p><!--
--><p>The name <i>Eleocharis</i> capitata (Linneaus) R. Brown was long misapplied to <i>E. tenuis</i> (H. K. Svenson 1939). Although the extremes of the three varieties are very different, intermediates are fairly common. Some plants are intermediate with <i>E. elliptica</i>.</p><!--
--><p><i>Eleocharis tenuis</i> belongs to the <i>E. tenuis</i> complex, which comprises species 16–21 and is restricted to North America, where it is widely distributed except for the Southeast and Southwest. <i>Eleocharis occulta</i>, <i>E. bifida</i>, and <i>E. nitida</i> are very distinct, have little variation, and have relatively restricted ranges; <i>E. tenuis</i>, <i>E. elliptica</i>, and <i>E. compressa</i> are difficult to separate, are highly variable, and have relatively large ranges (see also discussions under <i>E. compressa</i> and <i>E. elliptica</i>). <i>Eleocharis occulta</i> and <i>E. bifida</i> are evidently closely related to <i>E. compressa</i>; they are known only from unglaciated areas south of the limits of Pleistocene glaciation, while <i>E. compressa</i> has a broad range in glaciated regions. The cytotaxonomic study by L. J. Harms (1972) of <i>E. tenuis</i>, <i>E. elliptica</i>, and <i>E. compressa</i> included artificial interspecific and infraspecific hybrids as discussed under those species.</p><!--
--><p><i>Eleocharis tenuis </i>var.<i> pseudoptera</i> might also be treated as <i>E. elliptica</i> <i></i>var.<i> pseudoptera</i> following L. J. Harms (1972) because it is intermediate between <i>E. tenuis </i>var.<i> tenuis</i> and <i>E. elliptica</i> <i></i>var.<i> elliptica</i> in most characters except for the 4-angled, usually deeply sulcate culms. It appears to intergrade with <i>E. elliptica</i>. It is placed in <i>E. tenuis</i> because many plants, including an isotype, are more like <i>E. tenuis</i> than <i>E. elliptica</i>; because most plants key more easily to <i>E. tenuis</i>; and to continue the use of the traditional name. The achenes of the holotype (from Lancaster county, Pennsylvania) and some other specimens closely resemble those of <i>E. elliptica</i> but are not obviously persistent after the scales fall. The usually diagnostic tooth on the distal leaf sheath in <i>E. tenuis </i>var.<i> pseudoptera</i> is also characteristic of <i>E. elliptica</i> <i></i>var.<i> elliptica</i>; but in <i>E. tenuis </i>var.<i> pseudoptera</i> it is more often present and usually longer and stouter than in <i>E. elliptica</i>. The culms of the holotype of <i>E. tenuis </i>var.<i> pseudoptera</i> and many other specimens are 4- to 5-angled, and in some specimens are very irregularly to 6-angled and often rigid and compressed. L. J. Harms (1972) transferred <i>E. tenuis </i>var.<i> pseudoptera</i> to <i>E. elliptica</i> because he counted the same 2n = 38 chromosome number in both <i>E. elliptica</i> and <i>E. tenuis </i>var.<i> pseudoptera</i> and produced artificial <i>E. elliptica</i> × <i>E. tenuis </i>var.<i> pseudoptera</i> hybrids in which meiotic pairing and pollen stainability were very high. A. E. Schuyler (1977) reported 2n = 39 for <i>E. tenuis </i>var.<i> pseudoptera</i> as well as 2n = 34 and 68 for a putative <i>E. tenuis </i>var.<i> tenuis</i> × <i>E. tenuis </i>var.<i> pseudoptera</i> hybrid.</p><!--
--><p>Putative hybrids between <i>Eleocharis compressa</i> and <i>E. erythropoda</i> of the <i>E. palustris</i> complex in Ontario have been reported (P. M. Catling and S. G. Hay 1993), and I have observed putative <i>E. compressa</i> × <i>E. erythropoda</i> and <i>E. elliptica</i> × <i>E. erythropoda</i> hybrids in the field in southeastern Wisconsin. It seems possible that introgression from <i>E. erythropoda</i> is responsible for some of the variation of both <i>E. compressa</i> and <i>E. elliptica</i>, especially the frequent presence of some 2-fid styles and lenticular achenes in both species and some (rarely all) entire floral scales in <i>E. compressa</i> (S. G. Smith 2001).</p>
|tables=
|references=
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Culms sharply angled, usually deeply sulcate, to 0.8 mm wide; some or all culms with distal leaf sheaths with stout apical tooth to 0.4–0.6(–0.9) mm; achenes usually lemon yellow to dark yellow, with 10–14 obscure to clearly evident depressions in each vertical series; tubercles mostly greatly depressed, much lower than wide.
|[[Eleocharis tenuis var. pseudoptera|Eleocharis tenuis var. pseudoptera]]
|-id=key-0-1
|1
|Culms bluntly angled to smooth, seldom deeply sulcate, to 0.5 mm wide; distal leaf sheaths without tooth or with slender apical tooth to 0.2 mm; achenes usually yellow to green or brown, with 6–12 depressions in each vertical series; tubercles as high as wide to greatly depressed.
|[[#key-0-2| > 2]]
|-id=key-0-2
|2
|Rhizomes 0.4–1 mm thick, longer internodes (2–)5–10 mm; tubercles as high as wide, sometimes greatly depressed; achenes finely rugulose and cancellate.
|[[Eleocharis tenuis var. tenuis|Eleocharis tenuis var. tenuis]]
|-id=key-0-2
|2
|Rhizomes (1–)1.5–2 mm thick, longer internodes 2 mm; tubercles greatly depressed, rarely pyramidal; achenes coarsely (to finely) rugose at 10X and usually cancellate at 10–20X.
|[[Eleocharis tenuis var. verrucosa|Eleocharis tenuis var. verrucosa]]
|}
</div></div><!--

-->{{#Taxon:
name=Eleocharis tenuis
|authority=(Willdenow) Schultes
|rank=species
|parent rank=series
|synonyms=
|basionyms=Scirpus tenuis
|family=Cyperaceae
|distribution=N.B.;N.S.;P.E.I.;Que.;Ala.;Ark.;Calif.;Conn.;D.C.;Del.;Ga.;Ill.;Ind.;Iowa;Kans.;Ky.;La.;Maine;Mass.;Md.;Miss.;Mo.;N.C.;N.H.;N.J.;N.Y.;Nebr.;Ohio;Okla.;Pa.;R.I.;S.C.;S.Dak.;Tenn.;Tex.;Va.;Vt.;W.Va.;Wis.
|reference=None
|publication title=Mant.
|publication year=1824
|special status=Illustrated;Endemic
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-data-curation.git/src/bb6b7e3a7de7d3b7888a1ad48c7fd8f5c722d8d6/coarse_grained_fna_xml/V23/V23_119.xml
|genus=Eleocharis
|subgenus=Eleocharis subg. Eleocharis
|section=Eleocharis sect. Eleocharis
|series=Eleocharis (sect. Eleocharis) ser. Eleocharis
|species=Eleocharis tenuis
}}<!--

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[[Category:Treatment]]
[[Category:Eleocharis (sect. Eleocharis) ser. Eleocharis]]
[[Category:Revision Pending]]