What does "dog grass" mean?

A coarse perennial grass, of species Elymus repens, common in uncultivated grounds

Dog grass

Common synonyms include: agropyron repens, couch grass, quack grass, quackgrass, quick grass, witch grass.

noun

noun ·Rare ·Advanced level

Noun

1
A coarse perennial grass, of species Elymus repens, common in uncultivated grounds uncountable
2
European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed wordnet