SETARIA VIRIDIS
22. Setaria viridis (L.) Beauv. Green Bristlegrass, Green Foxtail, Bottle grass.
A coarse annual, semi-erect and branching from the base; common weed of waste places, cultivated fields and gardens.
Leaves rolled in the bud-shoot. Sheath cylindrical or slightly compressed, not keeled, glabrous but sometimes sparse-appressed pubescent, light green or tinged with purple towards base, split; margins pubescent with hairs about 1 mm. long (where the margins overlap the inner one is glabrous). Auricles absent. Collar broad, distinct, continuous, yellowish green or tinged with red, pubescent along base. Ligule a fringe of hairs 1 to 2 mm. long, fused at base, with the longer hairs towards the edges. Blade 4 to 10 mm. wide, 5 to 20 cm. long, flat, not keeled, gradually tapering to a sharp tip, not ridged but midvein prominent, glabrous, green, scabrous; margins serrulate-scabrous.
S. viridis is readily distinguishable from S. lutescens by the ciliate margins of the sheath and absence of twisted hairs at the base of the blade. The ligule is longer, the sheath is not compressed and is of firmer texture than in S. lutescens.