Setaria viridis

Setaria viridis is a species of grass known by many common names, including green foxtail, green bristlegrass, and wild foxtail millet. It is sometimes considered a subspecies of Setaria italica. It is native to Eurasia, but it is known on most continents as an introduced species and is closely related to Setaria faberi, a noxious weed. It is a hardy grass which grows in many types of urban, cultivated, and disturbed habitat, including vacant lots, sidewalks, railroads, lawns, and at the margins of fields. It is the wild antecedent of the crop foxtail millet. This is an annual grass with decumbent or erect stems growing up to a meter long, and known to reach two meters or more at times. The leaf blades are up to 40 centimeters long and 2.5 wide and glabrous. The inflorescence is a dense, compact, spikelike panicle up to 20 centimeters long, growing erect or sometimes nodding at the tip only. Spikelets are 1.8–2.2 mm long. Each is subtended by up to three stiff bristles. Its fertile lem......read more on Wikipedia.