Dame’s rocket: the main phlox lookalike
The plant most often mistaken for phlox is Dame’s rocket (Hesperis matronalis), also called sweet rocket. It has clusters of fragrant purple, pink or white flowers in late spring and early summer, which is why it is often assumed to be wild phlox. Dame’s rocket is a member of the mustard family, native to Europe and Asia, and was brought to North America as a garden ornamental. It has spread in many northern states and Canadian provinces, especially along roadsides, woodland edges and stream banks, where it can crowd native wildflowers.
Because it is pretty and was sold in “wildflower” seed mixes, many people do not realize it is a problem. For how invasive status is defined, see invasive vs aggressive plants.
How to tell Dame’s rocket from phlox
| Feature | Dame’s rocket | Native phlox |
|---|---|---|
| Petals | 4 petals per flower | 5 petals per flower |
| Leaf arrangement | Alternate along the stem | Opposite, in pairs |
| Leaves | Lance-shaped, toothed, somewhat hairy | Smooth-edged, narrower or oval |
| Plant family | Mustard | Phlox |
| Seed | Long, slender seed pods | Small capsules |
| Bloom time | Late spring to early summer | Varies by species; woodland phlox in spring, garden phlox in summer |
The petal count is the easiest test. Count the petals on several flowers; flowers can be crumpled or oddly shaped, so check more than one. Also look at where leaves attach: if they are staggered, you are probably looking at Dame’s rocket.
Should you pull Dame’s rocket?
Many extension and conservation sources recommend removing it. Practical tips:
- Time it before seed set. Pull plants while in bloom or before seed pods form, since each plant can produce many seeds.
- Pull when soil is moist so the roots come up. It is a biennial or short-lived perennial, and pulling is practical for small patches.
- Bag flower heads and seed pods and dispose of them in the trash rather than composting.
- Watch the site for a few years. Seeds in the soil can sprout later, so repeat removal.
- Replace it with native plants so it does not return.
If you are unsure whether it is Dame’s rocket, take photos and ask local extension before removing a plant you might want to keep.
What plants look like creeping phlox?
Creeping phlox (Phlox subulata) forms a dense mat of needle-like leaves covered in spring flowers. A few plants resemble it:
- Rock cress (Arabis) and Aubrieta have four-petaled flowers, unlike phlox’s five.
- Rock soapwort (Saponaria ocymoides) has five pink petals and a trailing habit, making it a close lookalike.
- Periwinkle / vinca (Vinca minor) forms mats with purple-blue flowers and glossy leaves, and is invasive in parts of North America.
Most of these are garden ornamentals rather than serious invaders, but whether any are a problem depends on your region.
Native phlox to grow instead
- Woodland phlox (Phlox divaricata): fragrant blue-lavender spring flowers, good for part shade.
- Creeping phlox (Phlox subulata): native to parts of the eastern US and a good groundcover in sunny spots.
- Garden phlox (Phlox paniculata): tall summer bloomer, native in the eastern US.
- Prairie phlox (Phlox pilosa): small pink-lavender flowers on prairie and woodland edges.
- Creeping woodland phlox (Phlox stolonifera): a low, shade-tolerant groundcover.
Choose species native to your area and confirm with a local native plant nursery.
What is the most invasive plant in the USA?
There is no single answer. Invasiveness depends on region, and lists differ between agencies. Species often mentioned as serious problems include kudzu in the Southeast, purple loosestrife and Japanese knotweed in wetlands and riparian areas across the North, and multiflora rose, Japanese barberry and bush honeysuckles in eastern woodlands. Our articles on Japanese knotweed lookalikes and invasive plants with red berries cover some of these. For the most useful list, look to your state’s invasive plant council.