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CommentsBecause of its large size and long nodding seedheads, mature plants of Giant Foxtail are quite conspicuous. It is one of several introduced Setaria spp. (Foxtail Grasses) that are weedy summer annuals. Giant Foxtail is larger in size than other Foxtail Grasses that occur in Illinois, and its seedheads are long and conspicuously nodding. Other Foxtail Grasses in the state have seedheads that are straight or nod slightly. The bristly hairs of Giant Foxtail's seedheads are always green before they become light brown or straw-colored. In contrast, young bristly hairs of Setaria glauca (Yellow Foxtail) are always yellow and those of Setaria viridis (Green Foxtail) are sometimes purple. Another grass species, Elymus canadensis (Canada Wild Rye), superficially resembles Giant Foxtail because of its large size and nodding bristly seedheads. However, the bristly hairs of Canada Wild Rye are even longer than those of Giant Foxtail, and they curve outward from its seedheads. In contrast, Giant Foxtail has straight bristly hairs on its seedheads.