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Hesperis matronalis L. (Family: Brassicaceae)

 

Dames rocket, a member of the mustard family, is often confused with garden phlox (Phlox paniculata). Unlike dames rocket, phlox species have opposite leaves and flowers with five petals, not four. Dame's rocket is often planted as an ornamental, but quickly escapes cultivation because of its prolific seed set. Unfortunately, part of its success can be attributed to its wide distribution in wildflower seed mixes, despite the fact that the U.S. Department of Agriculture has declared it a noxious weed. The plants are prolific bloomers and produce large quantities of seed from May into July, enough to ensure it develops large colonies. Each plant may have several clusters of flowers at various stages of development, enabling the plant to produce both flowers and seeds at the same time!

 

Also known as: Dame’s rocket, dame rocket, sweet-rocket, Dame’s violet, damask-violet, Dame’s gilliflower, night-scented gilliflower, queen’s gilliflower, rogues-gilliflower, winter-gilliflower, summer lilac, mother-of-the-evening

 

Origin: Dames rocket is native to Eurasia but was introduced to North America as a garden plant during the Colonial period, probably on the East Coast. It easily escaped cultivation and began to spread. It is still used as a landscape plant and has become so common that many mistakenly believe that it is a native wildflower.

 

Description:

  • Dames rocket is a showy, short-lived perennial or biennial. Generally, plants produce a basal rosette the first year and flower the following year. Mature plants will flower, produce seed, and die by midsummer.

  • Stems can be 2-3 feet tall and may be branched.

  • Leaves are alternately arranged, oblong, and hairy on both sides. They have small sharp teeth and long-pointed tips and decrease in size as they ascend the stem.

  • Dames rocket blooms from May to August with large, loose clusters of white, pink, or purple flowers that have 4 evenly-spaced petals. The flowers are fragrant, especially in the evening

  • Dames rocket fruits are long, narrow structures called siliques that begin to form in June. Siliques become tan and papery as they mature and contain many shiny black seeds in a row. At maturity, the fruits split open from the bottom to the top, releasing the seeds and leaving a thin membrane in the middle. The seeds are eaten and spread by ground-foraging birds.

 

Distribution: Dames rocket is now found throughout Canada and the United States, except for the extreme southern states. It typically grows in moist and mesic woodlands, woodland edges, roadsides, railroad right-of-ways, fencelines, open areas, thickets, waste ground, or disturbed sites. Problem: Generally, dames rocket can crowd out and displace native species. Although it is not yet a large-scale invasive, it can spread rapidly from seed and form dense patches. Its impacts are not yet well known; in fact, it is not yet widely recognized as an invasive species in the Midwest.

 

Control: Be sure to check the contents of wildflower seed mixes for dames rocket, and do not plant those that contain it. If it is already present in an area, hand pulling or digging out the plants with a dandelion digger immediately before seeds develop is the best way to prevent their spread. The plants can be bagged or dried and burned. Pulling may need to be done for several years to remove new plants that become established from the seed bank. Alternatively, selectively applying a broadleaf herbicide such as glyphosate may be an effective means of control. Herbicide should be applied in late fall when the rosettes are still green to avoid damage to adjacent native vegetation.

 

USE PESTICIDES WISELY: Always read the entire pesticide label carefully, follow all mixing and application instructions and wear all recommended personal protective gear and clothing. Contact your state department of agriculture for any additional pesticide use requirements, restrictions or recommendations.

Dames rocket