Ragweed, and Whealkate Bluff

2020 March 22

Back on October 1, 2019, I decided to take some pictures of the ragweed that grows alongside our road. This particular enormous specimen was down at the base of the hill, and stood over three feet tall.


The leaves are “ragged”. The ones I have seen around Michigan all my life are like this one, with deep notches to the point that it almost looks like it has compound leaves. This makes me think it is the Common Ragweed, Ambrosia artemisiifolia. There are lots of other ragweed species, though, with varying degrees of leaf notching.


The most distinctive feature is the blossom spike, projecting straight up with the small, inconspicuous flowers underneath a hood structure.


Ragweeds are wind-pollinated, so they don’t do anything to attract pollinating insects. Instead, the blossoms are shaped to keep pollen dry until the wind blows, and then shake to disperse it on the wind.


The problem with wind pollination is that it is woefully inefficient, which means that each plant has to dump a huge amount of pollen into the air to have a reasonable chance of reaching another ragweed flower. The combination of large quantities of pollen that is also fine enough to stay suspended in the air for a long time is basically a recipe for an allergen. And boy, are a lot of people allergic to these. There are estimates that up to half of all allergic rhinitis cases in North America are due to ragweed allergies[1]. It’s widely considered a noxious weed for this reason, although it is a native North American species, so at least we can’t complain about it being another invasive.

And now for a complete change of topic, for no reason other than that this was the next set of pictures on my camera:

A few days later on October 7, 2019, we climbed up Whealkate Bluff, a fairly tall Glacial Kame[2] just a few miles from our house, and I got this picture of the leaves just starting to change:


The total elevation at that point is close to 1400 feet above sea level, or about 600 feet above the surrounding ground. This is high enough that you can see for quite a long way. The blue patch on the left horizon is Lake Superior just off of McLain State Parks (about 20 miles away). Whealkate is a bit unusual for our area in that there is a clear view from the top, unobstructed by vegetation. And the reason for the view being unobstructed is this:


Whealkate is the site of a number of snowmobile and dirt bike “hill climb” competitions. It is really steep, in places it is probably close to an 80 degree slope. And the track that they climb has cut a trench up the face of the hill, making a vegetation-free slot so you can look across the countryside. We tried sledding on it a few times, but it is just too steep. We could get started OK with the sled underneath, but we would quickly lose control of the sled and just kind of controlled-fall down the side of the hill.

[1] When I was a kid, I read a series of stories by Robert McCloskey that he wrote in the 1940s that feature Homer Price. One of them was about the local disreputable character inheriting his botanist uncle’s greenhouse along with a mysterious container of seeds labeled only as “Experiment 13”, which he promptly planted in the hopes that it would grow up to something profitable. Homer and his buddy were hired to look after the plants, which turned out to be absolutely enormous (to the point that they had to knock holes in the greenhouse roof to allow them to keep growing). But, nobody knew what they were, until Homer realized that everyone had been misled by the sheer scale of the plants and that they were actually gigantic ragweeds that were going to bloom in a few days. Panic immediately ensues . . . These books were a bit hard to find for a long time, but I see that they are now both available on Amazon as ebooks.

[2] A kame forms as a glacier melts. Basically what happens, is glaciers moving across the countryside plow up a lot of dirt, gravel, and boulders, until the whole thing is basically just dirty ice. Then when it melts, you get a pothole in the glacier that the meltwater runs into. The meltwater carries dirt into the pothole, and between the relatively warm water and the sunlight absorbed by the dirt, the hole keeps melting faster than the rest of the ice until it runs all the way through the glacier down to the ground. Water keeps draining into the hole, making a bigger and bigger pile of rocks and dirt. And finally, when the glacier finishes melting away, the site of the original pothole is now this big, dome-shaped hill. If the glacier is sufficiently deep, the kames can get really tall, but they are always just a pile of gravel with no solid rock core.

These are not to be confused with the other common hilly features left by glaciers, like moraines (dirt bulldozed forwards or to the sides by the leading edge of the advancing glacier), eskers (debris deposited by rivers running under the ice), and drumlins (elongated hills that are believed to form underneath the ice when glaciers melt extremely fast).

4 Responses
  1. Carole permalink
    March 22, 2020

    Hear that ragweed seeds are a favorite of quail.

    If that hill was in Florida, with our sandy soil, there would be a real erosion problem, hope that doesn’t happen in Michigan. Such an eyesore.

  2. April 7, 2020

    Off topic: Ohioan at Heart has created his own model of the Coronavirus pandemic. Interesting stuff.


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  4. September 26, 2020

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