Dame’s Rocket (Hesperis matronalis L.)
Family: Mustard (Brassicaceae)
Regulated: Importation and propagation/sale prohibited (January 1, 2006).
Identification: An erect biennial or perennial 5-10 dm (1.5-3′) in height. Leaves are alternately arranged on the stem, 5-10 cm (2-4″) long, lanceolate to lance-ovate in shape, and sharply toothed. Leaves higher on the plant are sessile or short-stalked, while lower leaves have obvious petioles. Leaves are usually hairy on both upper and lower surfaces, with the lower hairs being chiefly branched. Fragrant flowers in terminal inflorescences appear in late May-June with the scent being most pronounced at the end of the day. Each flower has 6 stamens and 4 purple, pink or white petals measuring about 2-2.5 en long. Fruits are long, slender pods 5-10 cm (2-4″) in length that contain many seeds in a single row on each side.
Habitat: Dame’s Rocket grows in full sun to full shade and can form dense stands, particularly in floodplains. It is commonly observed in riparian habitats and wetland areas, as well as in open woods. It also occurs alone roadsides, woodland borders, thickets and in waste places.
Threat: Although not native to North America, it is sometimes sold as part of “native” wildflower seed assortments. This plant’s capacity for high seed production and rapid spread allows it to outcompete native vegetation and dominate natural areas.
Distribution: It occurs in all regions of Massachusetts and throughout New England.
Similar Species: A variety of Phlox species such as Garden Phlox (Phlox pa niculata) may be confused with Dame’s Rocket. Identify Phlox by its five petals (as opposed to four) fused into a corolla. It can sometimes be seen growing with another non-native member of the mustard family, Honesty or Money Plant (Lunaric annua), which also has purple to white flowers, but can be distinguished by its round, coin-shaped fruits and triangular ovate leaves.
For additional information about Dame’s Rocket, see Dame’s Rocket.