ambrosia_trifida.jpgThis week, I decided to post about a plant I saw in Sonderman Park instead of doing another update on Monument Valley Park. It’s giant ragweed, and living up to its name, it is nearly 9 feet tall! (When I first encountered the plant in a Native Plant Masters course, our specimen was only 2 feet tall. It’s amazing what some rain can do.) It was so big, that at first I had a hard time identifying it. And then I realized, “Oh my gosh….this is giant ragweed!” The park does have the western ragweed, a smaller plant with more deeply lobed leaves, as well. If you’ve pulled ragweed from your garden, the western variety is probably the one you’ve dealt with (I’ve pulled hundreds of these over the years at the utility company’s xeriscape demonstration garden).

To find this plant, park in the Beidleman Center parking lot, and proceed into the park. After you cross the small footbridge over the creek, the giant ragweed patch is about 30 yards ahead and on your right (the first side trail to the right starts there).

This plant has leaves with three-to-five distinct lobes. A closer look reveals that some of these lobes have even split into three lobes of their own as well. The patch includes a few shorter plants as well, and I gently tapped on the flowers at the top (these are not showy flowers at all) and was rewarded with a soft puff of pollen. Clearly, I am lucky enough to not be allergic to ragweed. Unfortunately, we learned that my husband (whom I asked to go back to the park with me to take the photo with me in it for size comparison) does. The poor guy was sneezing strongly within a few minutes of being near the huge plants, and it was not windy at all.

ambrosia_trifida2.jpgThis leads me to flowers and allergies. Many people are sure they are allergic to goldenrod (Solidago spp.) or other showy flowers that are blooming this time of year. Plants with showy flowers actually have large, heavy pollen granules, and they need pollinators like bees to carry that pollen to other plants. This type of pollen is not the cause of hay fever or sneezing allergic reactions. Instead, remember how I said the ragweed flower was not very showy? Well the plants that really cause our sneezing allergy problems have small, inconspicuous flowers, and the pollen they produce is very tiny and light. They rely on the wind to blow the pollen to other plants. And that wind-born pollen is easily caught in our nasal passages when we breathe. So…the reason people believe they are allergic to plants like goldenrod is that the poor goldenrod blooms at the same time as ragweed does. Nobody notices the ragweed blooms, but they DO notice the goldenrod flowers and make the logical assumption that they are the cause of their troubles! Some other plants that are wind-pollinated and cause hay fever are artemisia, lamb’s quarters, pigweeds, amaranth, etc. And many trees are wind-pollinated as well – junipers (this one I AM allergic to), aspens, and cottonwoods are a few examples.

If you have time, continue walking around the park, and you’ll be able to see honeysuckle berries, lots of chokecherries, and even a wild plum!

Text and photos contributed by Carey Harrington, Colorado Native Plant Master

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