Quackgrass     Biology: Quackgrass ( Elymus repens) is a cool-season perennial that vigorously spreads by rhizomes. It is a sod-forming grass that can crowd out desirable grasses and even other weeds. Quackgrass has been shown to be allelopathic, which means it releases chemicals that inhibit the growth of other plants. Large, nearly pure patches of … Continue reading Quackgrass