Setaria viridis (L.) P. Beauv.
Family - Poaceae
Stems - To 2.5m tall, erect to spreading at the base, herbaceous, multiple from the base, from fibrous roots, glabrous.
Leaves - Blades to 40cm long, to 2.5cm broad, flat, scabrous adaxially, scabrous to glabrous abaxially, entire. Margins ciliolate at the base, often purplish near the base of the leaf. Sheaths with cilia on the margins, glabrous to scabrous. Ligules of hairs, to 3mm long.
Inflorescence - Terminal. Spike-like but actually paniculate with many short alternate branches, to 20cm long, erect or nodding near the apex. Lowermost 2-3 branches of the inflorescence typically slightly separated from the rest of the inflorescence. Axis of inflorescence with short and long antrorse hairs. Spikelets subtended by 1-3 stiff bristles. Bristles green to purple, to 1.2cm long.
Flowers - Spikelets to 2.5mm long. Lower glume to 1.2mm long, glabrous, green. Upper glume to 2.2mm long, glabrous, green. Glumes mostly ovate, blunt to somewhat acute at the apex. Fertile lemma to 2.1mm long, with fine transverse wrinkles, glabrous.
Flowering - June - October.
Habitat - Margins of mesic upland woods, upland prairies, streambanks, pond margins, pastures, fields, lawns, cultivated areas, disturbed sites, roadsides, railroads.
Origin - Native to Eurasia.
Other info. - This weedy species can be found throughout Missouri. It is a variable species and two varieties are recognized in Missouri. Variety major (Gaudin) Posp. grows to 1.4m tall and is a more robust and stout plant. The leaf blades of this variety grow to 40cm long and 2.5cm broad. Variety viridis is a taller, thinner plant which grows to 2.5m tall. The leaf blades of this variety grow to 25cm long and 1.5cm broad.
Photographs taken in Van Buren, MO., 7-19-03.