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Danger from the stranger in the garden

  • Blog Post by: Mary Jane Smetanka
  • June 17, 2013 - 10:50 AM

This spring I noticed an attractive little stranger in the garden. The leaves looked kind of cool, so I let it grow.
Last week, the now-tall stranger bloomed. The emerging lavender flowers had the delicious spicy smell of stocks, which I had tried to grow a couple of times without much luck. Could this be some weird seedling from those plants?
When I got on the Internet, I realized I had something totally different: Hesperis matronalis, better known as dame’s rocket. As my plant grew taller — this morning it was a sturdy four feet tall — the tight ball of fragrant flowers grew spiky and loose, and I recognized my dame’s rocket as the same plant I see growing in ditches and in glades along West River Parkway along the Mississippi River.
Dame’s rocket is in the same plant family as garlic mustard, one of the most noxious weeds in the Twin Cities area. My beautiful visitor is banned or listed as a noxious weed in Colorado, Connecticut and Massachusetts, and in Michigan people who remove garlic mustard from the landscape are encouraged to take its cousin, too.
Here’s some more information about dame’s rocket: http://www.nps.gov/plants/alien/pubs/midatlantic/hema.htm. While it resembles wild phlox, it can be identified by its four-petalled flowers.
After I took this picture, I reluctantly pulled the plant up. It is very shallow-rooted, but dame’s rocket prolifically spreads through seeds, and I didn’t want my plant to populate my perennial garden.
I will be curious to see if dame’s rocket is eventually added to Minnesota’s list of noxious weeds.
Have you found visitors in your garden that turned out to be thugs instead of friends? This weekend another master gardener told me she lets dame’s rocket grow in her boulevard garden where it thrives in a hostile space. One gardener’s enemy is another gardener’s friend! Here’s a nice column on that issue: http://www.nytimes.com/2008/06/12/garden/12qna.html.

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