(Hesperis matronalis), Eurasian plant of the mustard family (Brassicaceae) that is widely naturalized in North America and Great Britain. A garden ornamental with flowers of violet-like fragrance, dame's rocket reaches about 90 cm (3 feet) in height. It bears narrow, toothed leaves and upright spires of four-petaled, usually distinctly veined, flowers of lilac, purple, or sometimes white.