View source for Couchgrass

{{Taxobox
| color = lightgreen
| name = ''Elytrigia repens''
| image = Kweek Elytrigia repens.jpg
| image_width = 240px
| regnum = [[Plant]]ae
| divisio = [[Magnoliophyta]]
| classis = [[Liliopsida]]
| ordo = [[Poales]]
| familia = [[Poaceae]]
| genus = ''[[Elytrigia]]''
| species = '''''E. repens'''''
| binomial = ''Elytrigia repens''
| binomial_authority = ([[Carolus Linnaeus|L.]]) [[Desv.]] ex [[Nevski]]
}}

'''''Elytrigia repens''''' ('''Couch Grass'''; [[synonymy|syn.]] ''Triticum repens'' L., ''Agropyron repens'' (L.) P. Beauv., ''Elymus repens'' (L.) Gould) is a very common species of [[Poaceae|grass]] native to most of [[Europe]], [[Asia]], and northwest [[Africa]]. Other names include twitch, quick grass, quitch grass, dog grass, and quackgrass.<ref name=grin>Germplasm Resources Information Network: [http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?102068 ''Elytrigia repens'']</ref><ref name=fnwe>Flora of NW Europe: [http://ip30.eti.uva.nl/BIS/flora.php?selected=beschrijving&menuentry=soorten&id=4625 ''Elytrigia repens'']</ref><ref name=foc>Flora of China: [http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200025323 ''Elytrigia repens'']</ref>

[[Image:Elymus.repens.jpg|left|thumb|Flower spike]]
It has creeping [[rhizome]]s which enable it to grow rapidly across grassland. The stems ('culms') grow to 40–150 cm tall; the [[leaf|leaves]] are linear, 15–40 cm long and 3–10 mm broad at the base of the plant, with leaves higher on the stems 2–8.5 mm broad. The [[flower]] spike is 10–30 cm long, with spikelets 1–2 cm long, 5–7 mm broad and 3 mm thick with three to eight florets. The [[glume]]s are 7–12 mm long, usually without an [[awn]] or with only a short one.<ref name=fnwe/><ref name=foc/><ref name=fitter>Fitter, R., Fitter, A., & Farrer, A. (1984). ''Collins Guide to the Grasses, Sedges, Rushes and Ferns of Britain and Northern Europe''. Collins ISBN 0-00-219128-8.</ref> <br clear=left>

There are three [[subspecies]], one of these with an additional [[variety (biology)|variety]]:<ref name=grin/><ref name=fnwe/><ref name=foc/>
*''Elytrigia repens'' subsp. ''repens''. Throughout most of the range of the species.
**''Elytrigia repens'' subsp. ''repens'' var. ''repens''. Awns usually absent or if present, very short.
**''Elytrigia repens'' subsp. ''repens'' var. ''aristata'' (Döll) P.D.Sell. Awns present, up to 15 mm long.
*''Elytrigia repens'' subsp. ''elongatiformis'' (Drobow) Tzvelev (syn. ''Elytrigia elongatiformis'' (Drobow) Nevski). Central and southwestern Asia, far southeastern Europe (Ukraine).
*''Elytrigia repens'' subsp. ''longearistata'' N. R. Cui. Western China (Xinjiang).

[[Hybrid]]s are recorded with several related grasses, including ''[[Elytrigia juncea]]'' (''Elytrigia × laxa'' (Fr.) Kerguélen), ''[[Elytrigia atherica]]'' (''Elytrigia × drucei'' Stace), and with the [[barley]] species ''[[Hordeum secalinum]]'' (''× Elytrordeum langei'' (K. Richt.) Hyl.).<ref name=fnwe/>