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Jewelweed’s Cross-pollination Strategy

10-1-13 bumblebee and jewelweed  092Jewelweed (Impatiens pallida), also known as Touch-Me-Not due to the sensitivity of its bursting seed pods, illustrates a strategy used by many flowers to promote cross-pollination. The male and female parts of the flower develop sequentially — first the male (stamen), then the female (pistil), so that they are not mature and receptive at the same time. The bumblebee in this photograph is squeezing into the spur of a Jewelweed flower in order to reach the sweet nectar it contains. In doing so, its back brushes against the strategically located, pollen-laden anther (tip of male stamen). When the bee enters another Jewelweed flower, if its pistil is mature, some of this pollen is likely to brush against the stigma (sticky tip of the female pistil), thereby cross-pollinating the flower.

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13 responses

  1. Kathie Fiveash

    Isn’t that similar to the bottle gentian you wrote about recently? So fascinating!

    October 1, 2013 at 1:18 pm

    • Yes, Kathie, just like Bottle Gentian!

      October 1, 2013 at 2:08 pm

  2. Louise Garfield

    I am not sure if it is a benefit to the flower to have male and female parts mature at different times (thank goodness, though, for the pollinators). If the flower has parts that mature simultaneously, it must either self-pollinate or the pollinator would take care of it in one fell swoop?

    October 1, 2013 at 1:59 pm

    • My guess is that self-pollination is much more likely in plants where both male and female parts mature at the same time. In order to prevent it, many flowers that have male and female parts maturing at the same time have pistils that are taller than the stamens, which somewhat helps prevent self-pollination.

      October 1, 2013 at 2:10 pm

  3. Mary, your photographs are always superb but this one is……particularly beautiful – and a wonderful example of nature ‘photo-journalism’ – all the story right in front of our eyes. Thank you!

    October 1, 2013 at 2:02 pm

  4. Excellent photo and natural history. Always enjoy your posts and learn something in the process.

    October 1, 2013 at 2:39 pm

  5. Al Stoops, Nelson NH

    I think this photo might be of Impatiens pallida, yellow jewelweed. Here in my part of New Hampshire we mostly have spotted jewelweed, Impatiens capensis. I believe the yellow jewelweed is more common in Vermont—likely it prefers the sweeter (more alkaline) soils over there.

    October 1, 2013 at 5:00 pm

    • You’re absolutely right — thanks so much, Al.

      October 1, 2013 at 6:55 pm

  6. I infer that the individual flowers (or plants) are not in sync with each other. (They don’t all have stamens at the same time, and some time later all have pistils.)

    October 1, 2013 at 6:21 pm

  7. kpmcfarland

    I have always liked these plants. Check out the second half of a blog I wrote recently about why these flowers dangle on a stalk.

    October 4, 2013 at 12:31 pm

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