Turritis glabra L.
Family: Brassicaceae
tower mustard, tower rock-cress
Turritis glabra image
Merel R. Black  
Etymology: Arabis: a Greek word used for "mustard" or "cress," and the Greek word for Arabia, perhaps referring to the ability of these plants to grow in rocky or sandy soils (?)
Plants: erect, biennial/perennial, 12"-60" tall forb; stems usually hairy toward the base and smooth above
Leaves: lance-like, clasping, smooth
Flowers: white, 4-parted, 1/8"-1/4"; inflorescence a tight, short cluster (raceme) of stalked flowers; blooms May-June
Fruits: long, thin, roundish pod pointing upward; seeds in 2 rows
Habitat: sun; dry; prairies, fields
Conservation Status: Native