[1] : The Collaborative International Dictionary of English v.0.48

quitch grass \quitch" grass`\ kwi^ch" gr.as`. properly
   quick grass, being probably so called from its vigorous
   growth, or from its tenacity of life. see quick, and cf.
   couch grass. bot.
   a perennial grass agropyrum repens having long running
   rootstalks, by which it spreads rapidly and pertinaciously,
   and so becomes a troublesome weed. also called couch grass,
   quack grass, quick grass, twitch grass. see
   illustration in appendix.
   1913 webster
see also:
quick couch grass agropyrum repens couch grass quack grass quick grass 
twitch grass 

[2] : The Collaborative International Dictionary of English v.0.48

couch grass \couch" grass`\ gr?s`. bot.
   see quitch grass.
   1913 webster
see also:
quitch grass 

[3] : WordNet (r) 2.0

couch grass
     n : european grass spreading rapidly by creeping rhizomes;
         naturalized in north america as a weed syn: dog grass,
          quackgrass, quack grass, quick grass, witch grass,
          witchgrass, agropyron repens
see also:
dog grass quackgrass quack grass quick grass witch grass witchgrass 
agropyron repens 

Grass >> G Words
Grass, definition of term: Grass
grass_pag1.html

Couch >> C Words
Couch, definition of term: Couch
couch_pag1.html

Grass Spider >> G Words
Grass Spider, definition of term: Grass Spider
grass+spider_pag1.html

Grass Widow >> G Words
Grass Widow, definition of term: Grass Widow
grass+widow_pag1.html

Grass Widower >> G Words
Grass Widower, definition of term: Grass Widower
grass+widower_pag1.html

Grass Roots >> G Words
Grass Roots, definition of term: Grass Roots
grass+roots_pag1.html

Blue Grass >> B Words
Blue Grass, definition of term: Blue Grass
blue+grass_pag1.html

Cotton Grass >> C Words
Cotton Grass, definition of term: Cotton Grass
cotton+grass_pag1.html

Bear Grass >> B Words
Bear Grass, definition of term: Bear Grass
bear+grass_pag1.html

Blue-Eyed Grass >> B Words
Blue-Eyed Grass, definition of term: Blue-Eyed Grass
blue-eyed+grass_pag1.html