Monday, September 22, 2008

Ragweeds and Other Plants That Make Us Sneeze

I've noticed people blowing their noses and their eyes are red and watery.

About 10 or 11 days ago, I heard an item on Charles Gibson's ABC Nightly about Ragweed Allergies. I googled Ragweed/allergies/ABC news and got the title "Research Links Allergies to Climate Change" by Gigi Stone. She says, "Ragweed season is at its peak , bringing bad news for more than 50 million Americans who suffer from allergies to this plant". It seems that research shows that the higher levels of CO2 seen in recent years, causes the plants to grow faster and produce more pollen. This immediately made me wonder about the status of Ragweed is at Selah, Bamberger Ranch Preserve. So I went out with my camera to where some of the Ragweed and Sumpweed plants are growing. I took quite a few photos but don't have them available to me now. The pictures in this post are actually SCANS made from the plants, and will provide some images for this, the first post on this subject. I will write another post with additional pictures and information when I'm home (next weekend).

Today is Sunday, and I'm sitting in my hotel room in Houston where I'm spending a couple of weeks getting radiation therapy. Even though I have my computer, I don't have the hard drive that has my photo library. However, these scans are on my laptop computer, so I do have some illustrations.

To start I need to share some information with you about the nature of the group of plants that produce lots of the kind of pollen that so many people are allergic to. First as members of the Sunflower family (ASTERACEAE) they have multiple flowers in each head. In this group they all contain minute grains of pollen that are carried on the wind and such tiny grains can be blown hundreds of miles on a breeze. Because there are so many varieties of plants in this group, while they are blooming there are always lots of pollen grains floating around, generally in late summer and early fall. When cold fronts start arriving regularly in the fall, they end the ragweed season.

The plant that is usually blamed for causing allergies blooms at the same time as Ragweed and looks like it would have lots of pollen. Goldenrod (Solidago sp.) is also in the Aster family but has large sticky pollen grains which aren't carried on the wind, but rather on the legs and bodies of bees or other insects.

On Selah, I found at least 4 different plants that have wind pollination and flowers that really don't look like flowers. Two of them are in these scans. Western Ragweed is shown in the two photos below. Giant Ragweed (Ambrosia trifida) is also found on the ranch. I have pictures on my hard drive at home, and will publish them on this blog when I'm back at the ranch. There is another plant that I have not gotten a correct identification for, but is clearly in the same group.

Western Ragweed (Ambrosia psilostachya) is generally found (at least at Selah) in dry areas and is often along the edges of roads. The male flowers are seen in a terminal spike on the top of each stem and the female flowers are found below along the stem in the axil of each leaf where it attaches to the stem. When they are pollinated the female flowers quickly develop a seed which has spines that cling to fur or feathers as animals pass by.

Western Ragweed has male flowers that produce an incredible number of wind blown pollen particles. If you click on this photo and get the large version you can see the pollen particles in the picture where they fell onto the glass surface of the scanner.

Narrowleaf sumpweed (Iva angustifolia) has very narrow leaves and the flower head has bracts that subtend each male flower. Note that the male flowers of Ragweed doesn't have the long skinny bracts along its flower stalk.
The male flowers of Narrowleaf Sumpweed in this scan don't show the stamen hanging down, but when the flowers are out, you can see them. In this scan they are enlarged a great deal.

I hope you're not an allergy sufferer. Some people find masks help if they are outside. There are medicines that may help too. If you stop to smell the flowers, don't try to smell Ragweed!

Illustrations are scans of plants placed on the window of the scanner, and scanned at at least 400 dpi, and some of the closeups on 4800 dpi.

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