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May 28, 2008

dame’s rocket: asset, or invader?

Filed Under annuals & perennials, from seed, nature 

I WAS GOING TO SIMPLY NOTE TODAY how much I like the moment (now) when dame’s rocket, or Hesperis matronalis, blooms wherever it wishes among alliums and other late-May-and-June things, adding shades of lavender to the borders in its casual, self-sown manner. And then I read up on it (damn this internet thing…so much information, not all of it good).

It seems that dame’s rocket, a short-lived perennial and prodigious sower, is taking up more than its share of the natural spaces it spreads itself into (read: becoming invasive). In my area it is common along roadsides and woodland edges, in the filtered light of those spots, and really breathtaking at its peak. My plants blew in from across the road. But some states, such as Wisconsin, are noting its invasive tendency: the fact that it “escapes cultivation” so easily and takes up space that natives then must yield. Dame’s rocket has been on our shores since the 1600s, so it is no newcomer, but it is not a native American species, hailing from Eurasia. It’s often sold in “wildflower” seed mixes, and in packs by itself.

What do you think about our responsibility as gardeners when it comes to growing plants that are non-native, and this enthusiastic? It’s a subject I have a fair degree of knowledge about, having collaborated on “The Natural Habitat Garden” with Ken Druse some years ago and pondered many times since. Including just the other day on this blog when Highvalleygirl asked about some barberries I posted. Frankly, friends, despite my semi-expertise, I do not know the answer to this one. Tough stuff, and worth talking about (no fisticuffs, though, please).

Comments

14 Responses to “dame’s rocket: asset, or invader?”

  1. theManicGardener on May 29th, 2008 12:38 am

    Ouch, that’s a tough one. At what point does a plant win the right to be called “native”? How many centuries does it take to earn that coveted label? I’m a staunch defender of native plants, but I don’t believe we can stop all change. It depends, I suppose, at least in part on how much damage the invader does. Oh help.
    –kate

  2. Joy on May 29th, 2008 6:39 am

    You have some gorgeous pictures on here ! .. Loved the morning light one .. awesome !
    I have grown Dame’s Rocket .. but had to move it out due to lack of room with my small gardens. Kingston has sown ditches and open areas with that plus natives .. and they do look amazing rather than just seeing greens weeds. I always notice them while driving by and think they look wonderful : )
    Joy

  3. margaret on May 29th, 2008 7:27 am

    @Kate: Welcome to A Way to Garden. “Oh help” is exactly the situation…well-said. Glad to see you here this morning.

  4. Andrew Ritchie on May 29th, 2008 12:42 pm

    Wow, it’s complicated. I guess one has to assess (and qualify) what “damage” it is doing and how extensive that damage is. Is it enough of an offense that it is a successful non-native plant that has a habit of springing up when and where it likes? Is there proof that native plants are feeling the pinch because of its presence? I don’t have an answer. Maybe it’s a matter of saying, “Time will tell?”

    At least it’s not as invasive as Purple Loose Strife, those beautiful spires of deep purple that are taking over marshlands all over North America.

    -Andrew

  5. Layanee on May 29th, 2008 1:27 pm

    What we have gained in this country with plant introductions may well outweigh the problems inherent within. If we consider everything native to the earth and introduce no extra terrestrial plant life forms could that suffice? Love the natives, love the exotics! Life here would be dull without tomatoes and broccoli to grow not to mention ornamentals!

  6. Dan Sealy on May 29th, 2008 4:25 pm

    Well, if it taking over out natural areas - not mention our gardens, we should refrain from planting it. Purple Loosestrife, English Ivy and bamboo all have wonderful attributes but if they endanger my native natural areas - let’s enjoy them in artwork and their native grounds.

    Ailanthus, one of the most invasive trees in the Eastern US has been here for hundreds of years, but it destroys American forests. Time in place does not qualify as native.

    We (Americans) spend hundreds of thousands of dollars and thousands of volunteer hours each year to keep invasive exotics out of natural areas including National Parks and nature preserves. Let’s do the right thing - it is not all about esthetics… natural biodiversity is important.
    Thanks for caring enough to post this.
    Dan

  7. margaret on May 29th, 2008 4:49 pm

    Welcome, Dan, to A Way to Garden. Lots to think about. I guess I want to believe we can garden with natives and well-behaved aliens, and frankly I never had any idea that Dame’s Rocket was considered anything but! So even a familiar, commonplace plant turns out to be somebody’s weed, as per the Wisconsin bulletin. Very interesting and provocative stuff.

  8. elizabeth on May 29th, 2008 7:24 pm

    after a recent trip through kentuckey and tennessee, i have been pondering this myself. i have lived in urban areas with beautiful, grown as specimen paulownia trees, but there they were scrambling among rocks, looking scraggly and taking up an alarming amount of space.
    i think avoiding invasive species is imperitive, because often it is out of human hands how quickly the seeds spread. and before planting something, it is good to check your states, and surrounding states list of invaders.
    (i do plant things that are not native…but fairly benign things, i think)

    i also find hybridized version of native plants worrysome. think of the recent wave of coneflowers in all sorts of subtropical colors. how certain are we that these will not cross breed and affect the natural population?

  9. Tim Abbott on May 31st, 2008 12:02 pm

    This is indeed a complicated subject, Margaret, and you have approached it with many of the right questions. I served for 6 years on the Massachusetts Invasive Plant Advisory Group, which included nursery & landscape professionals, scientists, academics, non profits and state agency staff. One of our most significant tasks was to develop objective criteria for assessing whether an introduced species should be considered invasive in the Commonwealth. You can read what I wrote about that process at http://greensleeves.typepad.com/berkshires/2006/01/born_of_a_shotg.html

    Many, certainly a large majority, of introduced organisms are not invasive. Those with the behaviors described in MIPAG’s assessment criteria often are. There are, of course, questions of degree, which for me come down to the vectors of spread, the difficulty and expense of control, and the implications of new invasions for biodiversity. Because Dame’s Rocket is wind dispersed, establishes itself in dense stand, and is particularly invasive in floodplains, it is listed as Invasive in Massachusetts. Rte 71 between Austerlitz, NY and Alford, MA along the Green River is a good example of what Dame’s Rocket infestations can become in our region.

    MIPAG’s process and criteria can be viewed at the following link: http://www.mass.gov/dfwele/dfw/nhesp/conservation/invasives/invasive_plant_info.htm

    Best wishes, Tim

  10. Kathy from Cold Climate Gardening on May 31st, 2008 7:34 pm

    The Dame’s Rocket is just getting started around here, and I was wondering the same thing myself: what exactly makes something invasive? Why do I not feel (on my own land) that Dame’s Rocket is invasive, but multiflora rose is? They are both fragrant, both beautiful in bloom, but those thorns–does it make it easier to call the rose bad? Or is it truly more invasive? Or am I deceived about the Dame’s Rocket? And that native goldenrod I am struggling to eradicate from a garden bed, does it have to jump “the pond” before it’s invasive? It can take over a field as easily as the Dame’s Rocket.

  11. Rick on June 1st, 2008 8:11 am

    Detrimental invasive for me is defined by a non-native plants who’s growth characteristics and reproductive habits become detrimental to indigenous plants. Many indigenous plants are invasive, but they are not so aggressive as to start to crowd out or desimate others within the local.
    Introduction of non-indigenous plants to other areas and locals that have resulted in a “Oh my God, what have we done…” result are legendary.

  12. diana on June 4th, 2008 1:43 pm

    I know here in the west there are some terrible invasives. Tamarisk(salt cedar,) for example is taking over some of the riparian corridors. It’s not just that it outcompetes the native cottonwoods and willows but it also concentrates salt in already saline soils to the point where nothing else will grow. This is detrimental to all species who rely on the natives. tamarisk is also a super water hog.

    In an urban area I wouldn’t worry about dames rocket. In fact, where I live I wouldn’t worry at all. I think you have to take it case by case but the class 1 & 2 invasives should not be planted where they can get any kind of foothold. Gardeners should bear some responsibility, if we don’t care, who will?

  13. Motyka on June 26th, 2008 4:05 am

    Dame’s Rocket is invasive. And it is beautiful, with a light, almost jasmine scent. Which leads me to filling vase after vase with this “wild flower” from the ditches without the guilt of picking native plants.

  14. margaret on June 26th, 2008 5:43 am

    Welcome, Motyka. How true, how true! Thanks for joining us at A Way to Garden, and hope to see you soon again.

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