If you traveled at all over the past week – even for a quick drive out of town or around the county – you likely saw pockets of beautiful purple and white blooms along woodlots, roadsides, water edges, and disturbed areas. You may have even exclaimed – the “phlox are out!” So beautiful!
Alas, the plant that is flowering profusely right now is Dame’s rocket. These flowers have fooled a many folk before from a distance, including myself. Dame’s rocket (Hesperis matronalis) resembles phlox in height and color but is in a different plant family entirely, the Mustard family (Brassicaceae) while Phlox is in the Phlox family (Polemoniaceae). Perhaps the most distinguishing difference between the two is that Dame’s rocket has four petals, while phlox has five.
Inflorescence of Hesperis matronalis with individual flowers having four petals, a characteristic of plants in the Mustard family.
Dame's rocket flowers varying in color from milky white to violet and shades in between.
In contrast, this Phlox paniculata hybrid has five petals per flower on each inflorescence.
The woodland wildflower Phlox divaricata also features five petals per flower.
While beautiful, dame’s rocket does have an invasive nature as evidenced by the prolific pockets of plants readily seen this time of year. Hesperis is an introduced plant to the US and can now be found in nearly every state, officially making the noxious weed lists in Colorado, Connecticut, and Massachusetts (PlANTS database.) While it is not on Ohio’s Noxious weed list, it does have a place on ODA’s Invasive Plants list along with 37 other plants that cannot be sold, propagated, distributed, imported or disseminated within the state.
Don't be fooled by the beauty of Dame's rocket. This plant will not make a great addition to Ohio cutting or perennial gardens. It's best to rogue any resident plants out now and in the future.