Answer: Quackgrass has long, tapered blades around 1/3 inch wide attached to hollow stems. The plant is much more upright growing than crabgrass. The seed heads are single, upright stems, not branched like crabgrass. Quackgrass has a strong root system with white, fleshy rhizomes that spread out from the main plant, sending up new plants.
It is green, not purple.
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