Any of several grasses, of the genus Panicum, often found as a weed(noun)
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Use "witchgrass" in a sentence
"Among species characteristic of this habitat are Russian thistle, cocklebur, witchgrass, inland Sea Rocket and velvetleaf."
"Digging and weeding and planting and tending my flowers, all this serves some primitive instinct, so that I feel much more like a pig rooting for truffles than a woman staking her delphiniums, or pulling up witchgrass, or transplanting phlox from a shady to a sunny spot."
"K'shar pushed aside the tangled witchgrass and gazed upon the half-metamorphosed milestone with curious golden eyes."