green foxtail
Setaria viridis                                        

Identifying Characteristics:

Seed:  oval to ovate in shape; palea covers over 1/2 of the seed; green to yellow in color; narrower and smaller than yellow foxtail seed

Seedling:  leaves rolled in whorl; glabrous stems and leaves; few scattered hairs on lower margins of the collar region; no auricles; short, membranous ligule with fringe of hair

Mature Plant: erect, bunch-type growth habit; dense, cylindrical panicle with stiff bristles; 3 or fewer bristles per spikelet

Method of Propagation: seed, short rhizomes

Life Cycle: warm-season annual

Similar Species: yellow foxtail - compare seed size and pubescence 

References: Abaye, A. Ozzie. "Identification & Adaption: Common Grasses, Legumes & Non-leguminous Forbs of the Eastern United States."
Bryson, Charles T. & Michael S DeFelice. "Weeds of the Midwestern United States & Central Canada."