Brassica nigra (L.) W.D.J.Koch
Family: Brassicaceae
black mustard
Brassica nigra image
Hugh H. Iltis  
Etymology: Brassica: Latin name for "cabbage"
Plants: erect, annual, 6"-60" tall forb; stems with rough hairs toward the base, smooth and hairless above
Leaves: stalked, not clasping, oval; lower leaves often lobed, upper leaves toothed
Flowers: yellow, 4-parted, 1/4" wide; inflorescence a rounded cluster (raceme) of stalked flowers; blooms June-Sept.
Fruits: 1/2"-3/4" long, thin, erect, 4-angled pod lying near the stem
Habitat: disturbed sites, fields
Conservation Status: Introduced - naturalized