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One-flowered Cancer-root Flowering

6-16-15 one-flowered cancerroot IMG_1268One-flowered Cancer-root (Orobanche uniflora), also known as One-flowered Broomrape, produces up to five flowering stalks, each of which bears a single, fragrant, white-to-lavender flower. Glandular hairs cover the petals and two bright yellow ridges inside the flower may act as nectar guides for pollinating insects (although this flower does self-pollinate). One-flowered Cancer-root has no chlorophyll in the scale-like leaves that grow on its underground stem, and thus is incapable of making its own food. This parasitic plant is classified as a holoparasite – entirely dependent upon other host plants for its nutritional needs. These host plants often include Sedums as well as plants in the Saxifrage and Aster families.

The tiny One-flowered Cancer-root seedlings, with their limited food supply, must find a suitable host plant within a few days of germinating or die. The search for a host by One-flowered Cancer-root is guided by chemicals released by the growing roots of the host species. Once a host plant is located, the One-flowered Cancer-root’s root hairs exude an adhesive substance that attaches its roots to those of the host plant. Enzymes break down the cell walls of the host, and a tuber-like connection (haustorium) forms between the vascular tissue of the two plants, allowing the movement of water, minerals and carbohydrates to flow in one direction, from host to parasite.

Other species in the genus Orobanche are considered harmful as they parasitize crop plants, which One-flowered Cancer-root does not do. (Thanks to Shiela Swett for photo op.)

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16 responses

  1. Fascinating! Who knew? Thanks! But “Shiela”?

    June 16, 2015 at 7:44 am

    • Are you questioning the spelling, Willem? “SHIELA. Often misspelled as Sheila. A name for a girl who is very pretty and have a good sense of humor. Smart and wise in life.”

      June 16, 2015 at 7:57 am

  2. Marilyn

    Holoparasite! Is Indian Pipe one of those?

    June 16, 2015 at 8:54 am

    • Marilyn

      Indian pipe: I looked it up. Not a true parasite – perhaps a vicarious one?! Lives off fungi that live off other plants.

      June 16, 2015 at 9:00 am

  3. Ellen

    What habitat does One Cancer root like?
    Asters and Sedums usually like sun but
    I see Indian Pipe and Squaw Root only
    in shaded woods.

    June 16, 2015 at 9:03 am

    • Hi Ellen,
      I’ve found it in wet fields, but it also grows in moist woods and along streams occasionally.

      June 16, 2015 at 2:18 pm

  4. Luane Clark

    Yes, fascinating! Animals have a natural draw on our interest, but your information on plants is absolutely stunning.

    June 16, 2015 at 9:17 am

  5. Rita Pitkin

    Mary – I have never seen one of these in all of my travels through fields, woods, and swamps. Curious as to where these grow. Thanks.

    June 16, 2015 at 11:43 am

  6. Moist forests, thickets and fields. It definitely likes its feet wet. It’s fairly uncommon, so I’m not surprised you haven’t run across it!

    June 16, 2015 at 2:16 pm

    • Rita Pitkin

      Thanks Mary. I’ll be looking for it.

      June 16, 2015 at 2:48 pm

  7. Wow! I just found some of this YESTERDAY in my hedgerow and was wondering what it was. Today, the indefatigable Mary Holland supplies the answer! Thanks!!

    June 16, 2015 at 5:10 pm

  8. Kathie Fiveash

    Well, I have to say that whoever named this flower (Cancer root? Broomrape? Ghostpipe?) had a macabre bent of mind.

    June 16, 2015 at 8:32 pm

  9. I found it once. When I went back soon after, it was already gone

    June 17, 2015 at 10:08 am

    • And I went back to where I took this photo a year later, and it wasn’t there…

      June 17, 2015 at 1:39 pm

  10. ️Missy Storrow

    I found this plant yesterday and posted on FB to see if anyone knew what it was and was told you had just posted this, thanks! I had never seen it, and it is growing in the grass on the edge of a path we keep mowed through hill and dale. I was surprised to not find any basal leaves, and it reminded me of Indian pipe stem a bit. It also felt orchard like. I’ll smell it today, sounds wonderful. If u want I can send you my photo, this is in Calais VT.

    June 19, 2015 at 8:24 am

    • Missy, the white, scale-like leaves are actually underground. Great find!

      June 19, 2015 at 8:59 am

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