Horticulture/Hesperis matronalis

Dame's Rocket, also known as Damask Violet, Dame's Violet, Dames-wort, Dame's Gilliflower, Night Scented Gilliflower, Queen's Gilliflower, Rogue's Gilliflower, Summer Lilac, Sweet Rocket, Mother-of-the-evening and, Winter Gilliflower (Hesperis matronalis) is a herbaceous perennial plant belonging to the mustard family, Brassicaceae. A native of Eurasia and cultivated as a traditional garden plant elsewhere, Dame's Rocket was brought to North America in the 1600s and has since become naturalized there; it is considered an invasive species in some areas.

Description
The plant is often confused with look-alike native phlox species in North America, but the former can be easily identified by its alternate (rather than opposite), toothed lanceolate leaves (5-15 centimetres in length, larger towards the base of the plant) and showy flowers, which have four rather than a phlox's five petals.

Reaching a maximum height of one metre (3 feet), Dame's Rocket shoots up quickly in spring and enters full bloom by May. The plentiful flowers, in elongate clusters atop strong hairy stalks, are large (2 cm) and vary in colour from white to lavender purple, some being a variegated intermediate between the two. A double-flowered variety is known. The flowers are also highly fragrant; the genus name Hesperis is Greek for evening, a reference to this plant's sweet aroma becoming evermore conspicuous towards evening.

The blooming season may last until August, but exceptionally warm weather can hasten the blooms' passing. Seeds are produced in long (5-10 centimetres) pods containing two rows of seeds separated by a dimple.

Growing Conditions
Moist soil with good drainage in full sun to partial shade is preferred, but the plants are undemanding and will quickly crowd out native wildflower species if given the chance to become established. Extensive monotypic stands of Dame's Rocket are visible at great distances.

Ecology
The successful spread of Dame's Rocket in North America has been attributed to its prolific seed production and because its seeds are often included in prepackaged "wildflower seed" assortments. Although the plants typically produce only a low-lying rosette their first year, in subsequent years blooming and seed production occurs in tandem throughout the blooming season. The plants are most commonly seen in roadside ditches, dumps and in open woodland settings. Dame's Rocket does however make for an attractive, hardy garden plant and probably does not pose a threat in urban settings.

Pests and Diseases
In Europe, Dame's Rocket is host to the caterpillars of several butterfly species, including the Orange tip (Anthocharis cardamines) and Cabbage White (Pieris rapae); and moths such as Plutella porrectella.