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One-flowered Cancer-root Flowering

6-20-17 one-flowered cancerroot 099

One-flowered Cancer-root (Orobanche uniflora), also known as One-flowered Broomrape, is now flowering  in fens — wetlands similar to bogs, but less acidic and more mineral-rich.  Covered with glandular hairs, its flower looks like it’s made of crystallized sugar. One plant produces up to five flowering stalks, each of which bears a single, fragrant, white-to-lavender flower.

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. A One-flowered Cancer-root seedling must find a suitable host plant (often sedums, saxifrages and asters) 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. (Thanks to Shiela and Steve Swett for photo op.)

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5 responses

  1. Janice Kelly

    Really interesting to see and read about the cancer root and its parasitic qualities.
    Your reports and photos are a great addition to the day and broaden one’s knowledge considerably. Thank you for all that you do.

    June 20, 2017 at 7:45 am

  2. Alice Pratt

    Amazing! Incredibly interesting.

    June 20, 2017 at 7:51 am

  3. Marilyn

    I’m intrigued by the knowledge and research that lead to this fascinating information.

    June 20, 2017 at 8:16 am

  4. Molly Hale

    Very interesting to learn how the Orobanche finds and attaches to its host plant! It’s mind boggling how the seeds of this uncommon plant can ever find a suitable place to grow. I found a patch of these on June 10 this year in Chesterfield, MA. It was not a wetland, but rather a shrubby moist area that is being maintained as early successional habitat. I was unfamiliar with this plant, so when I first found it I thought the leaves around it were part of this plant. Now I see that they must be the host plant for the Orobanche. The leaves look like goldenrod to me, but maybe they are aster. Can you tell, Mary? Also The flowers I found were white with no lavender color. I’d attach a picture but I don’t see a way to do that in this comments section. I love your column!

    June 20, 2017 at 8:31 am

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