Rorippa palustris (L.) Besser  
Family: Brassicaceae
bog yellow-cress, common yellow-cress
[Radicula palustris (L.) Moench, Rorippa palustris var. X reptabunda (L.) Besser]
Rorippa palustris image
Corey Raimond  
Etymology: Rorippa: an Anglo-Saxon word rorippen whose meaning has been lost
Plants: erect, annual/biennial, 18"-40" tall forb, larger plants with many branches; taprooted
Leaves: lower leaves pinnately-divided; middle leaves with distinct wings and lobes toward the base, appearing stalkless
Flowers: yellow, 4-parted, 1/8"-3/8" long, petals about the same length as the sepals; inflorescence a loose cluster (raceme) of stalked flowers; blooms May-Oct.
Fruits: longish, plump pods about 2 times as long as its stalk
Habitat: generally in wetlands
Conservation Status: Native
Rorippa palustris image
Corey Raimond  
Rorippa palustris image
Emmet J. Judziewicz  
Rorippa palustris image
from USDA Plants website  
Rorippa palustris image