Lindernia dubia (L.) Pennell  
Family: Linderniaceae
false pimpernel, moist bank pimpernel
Lindernia dubia image
Corey Raimond  
Etymology: Lindernia: for Franz Balthasar von Lindern (1682-1755)
Plants: erect, annual, 2"-8" tall forb, stems branched
Leaves: opposite, mostly entire or with tiny teeth
Flowers: white to violet, 5-parted, 1/4" long, irregular shape, upper lip slightly 2-lobed and much narrower than the somewhat backward pointing, 3-lobed lower lip; solitary from the leaf axils; blooms July-Sept.
Habitat: wet; river banks, lakeshores; in sandy soil
Conservation Status: Native
Lindernia dubia image
from USDA Plants website  
Lindernia dubia image
Robert W. Freckmann  
Lindernia dubia image
Emmet J. Judziewicz  
Lindernia dubia image
Emmet J. Judziewicz