Photo of the Week – August 19, 2011

No, someone didn’t toss a mess of orange plastic twine out in the prairie, though that’s certainly what it looks like.  That crazy jumble of orange is the parasitic plant called dodder (Cuscuta sp.).  It has no chlorophyll, so is unable to photosynthesize – hence the non-green color.  Instead, it attaches itself to its host plants and extracts food from them.  The dodder in our prairies appears to favor goldenrod and sunflower species.

A patch of parasitic dodder on Canada goldenrod in a restored Platte River prairie, Nebraska.

Dodder has no leaves, and only tiny flowers that produce tiny seeds.  We’ve never harvested the seeds, but dodder shows up in our restored prairies anyway.  I think that’s great.  The fact that a parasitic plant can find and colonize amongst its host plants is just another indication that our restored prairies are functioning well.  I’ve never been able to find anyone who knows much about how its seeds travel, but there is a lot of speculation that they hitch rides on people, equipment, and animals.  Whatever – it seems to work!

I have a soft spot for species like dodder that have made their own counter-culture way in life.  (I no longer remove cowbird eggs from grassland bird nests for the same reason – so sue me.)  A plant that doesn’t even have leaves?  What a great idea!  Why make your own food if you can get it from someone else??

I’ve never seen evidence that dodder is eaten by anything, though I have to assume that something feeds on it.  Otherwise, we’d probably be swimming in dodder – and that might reduce its attraction to me just a little!

20 thoughts on “Photo of the Week – August 19, 2011

  1. Stephanie Frischie August 19, 2011 / 8:00 am

    What’s not to like about a plant that parasitizes Canada goldenrod? Maybe it is arriving in your restorations through traveling seed, maybe it is in the seed bank. Here in NW Indiana, I see the common dodder species along roadsides and fences as well as in the interior of quality natural areas. We have planted small quantities of seeds at Kankakee Sands, but I haven’t observed a direct result of more dodder in the plantings.

  2. Brady Allred August 19, 2011 / 8:58 am

    According to a 1999 PNAS* article, only 8-10 of the ca. 150 species of Cuscuta lack chlorophyll and do not photosynthesize. Even though the one in the photograph lacks visible green pigment, odds are it is photosynthetic to some degree, though still receiving resources from its host plant. The lack of leaves is apparently also debatable, as some suggest no leaves* and others leaves reduced to minute scales** (neither of which have any further citations on the subject).

    A 2011 Biological Invasions article*** also showed that in China, Cuscuta australis ‘restrained’ exotic species and benefited native species. Haven’t read the paper, so I’m not sure what that means.

    *found at http://dx.doi.org/10.1073/pnas.96.3.1135
    **found at http://dx.doi.org/10.1007/s004250050349
    ***found at http://dx.doi.org/10.1007/s10530-010-9865-x

    • Chris Helzer August 19, 2011 / 6:29 pm

      I love having scientists reading the blog! Great citations, Brady – thanks.

  3. David August 19, 2011 / 10:00 am

    Chris,

    Do you see any reduced vigor in the dodder host plants?

    David

    • James C. Trager August 19, 2011 / 2:54 pm

      Not sure what Chris is seeing up there, David, but down here in eastern Missouri, I have noticed some reduction of the height and flower production in patches of goldenrod that are heavily infested with dodder (also in Maximilian sunflower).

      • Chris Helzer August 19, 2011 / 6:27 pm

        I think I’ve seen the same, but honestly can’t say for sure. I’ll have to try to pay better attention. I normally see the dodder prior to blooming of the host plants or well after the dormant season has begun (when the coils of seed heads are all that’s left of the last season’s dodder).

        • MrILoveTheAnts August 20, 2011 / 12:57 am

          Reduced size to tall goldenrod and perennial sunflower species!? Does that stuff transplant well? I’m going to plant that in my garden!

      • Anna August 19, 2011 / 4:29 pm

        Similar to ivy or other climbing vines??

        • James C. Trager August 22, 2011 / 3:00 pm

          It resemble some other viney plants, especially morning glories (bindweed) in its clambering growth habit. But, leafless, chlorophyll-less, and rootless once it finds a host plant, it is quite different in appearance.

  4. Danelle Haake August 19, 2011 / 3:09 pm

    We have at least two varieties of dodder (at least, I assume they are different species based on differences in color and bloom time) at LREC in St. Louis. The orange variety on the edges of our prairie seems to highly favor wingstem, though an occasional brown-eyed Susan or jewelweed will play host.

    I have recently noticed a yellow variety that is attached to the Japanese hops along our streambanks. I am very grateful to this yellow species, as the hops is a horrible invasive that is an annual battle regionally in our riparian areas and along train right-of-ways. While the prairie plants have not shown much ill effect, the dodder certainly knocks back the hops!

    • James C. Trager August 22, 2011 / 2:57 pm

      No David, they have to already be attached by their feeding structures.

      MrILTA – You just need to cut those plants down to about knee- or thigh-high by August 1, and they’ll come back shorter and branchier.

      • David August 23, 2011 / 6:36 am

        James,

        Thanks for taking the time to answer questions!

        David

  5. Dave Wedin March 27, 2012 / 9:45 pm

    Hi Chris
    After my dad retired, he spent time as a consulting agronomist in eastern Europe. Dodder is a major problem in alfalfa and was spreading badly as agronomic standards dropped during the post-communist free for all. The problem is that dodder seed is very similar in size and weight to alfalfa seed. Once alfalfa seed is contaminated, it’s difficult to clean. Their solution in Croatia was to mix fine iron shavings with the seed and then pass it over a magnet. I think the story was that the fine shavings stuck to the rough seed coat of the dodder but not the alfalfa, allowing separation of the dodder. This has nothing to do with prairies…….but maybe there’s a tip for processing seed in the anecdote.

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