Our Native Tumbleweed

Our Native Tumbleweed

A common plant found on Lake Michigan dunes is a tumbleweed.  It has one of the more colorful common names, Winged Pigweed, and the Latin name is Cycloloma atriplicifolium. It is the sole species of its genus and is unrelated to the iconic tumbleweeds out west which are surprisingly not actually native.

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This year and last, Winged Pigweed is most visible growing in the newest erosion control area.  They grow in a round mound, green and lushly distinctive in the summer compared to the sparsely-spaced and spiky grasses.

Tumbleweeds are not one species or even one genus. The word tumbleweed describes a functional, behavioral aspect of any plant that “tumbles”.  Tumbling provides for seed distribution.  This is how it happens.  The plant dries out, breaks off at the root and, because it is dry, light weight, and round-ish the wind can catch it and move it.  The seeds themselves are not light enough to be windblown, but when the entire plant is blown by the wind the seed may be widely disseminated although the seed is neither light enough nor aerodynamic enough to be moved on its own.  As a group, plants that behave like this when they dry out can be aggressive. Just this year there was a building in California that was literally buried in the non-native sort of tumbleweed.

The Winged Pigweed is an annual, meaning that it grows from seed every year.  It is often as wide as it is tall.  It has a single stem, which, when it dies and dries out in the fall will snap, allowing the plant to blow around like a tumbleweed.  Some years you will see them all pushed up against the dune fence.

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Winged pigweed grows well on disturbed sand.  The plant is generally from west of the Mississippi, but due to its preference for disturbed ground it has spread widely on the Continent.  Because sand dunes would have always provided ideal habitat, it is believed to have been native to Lake Michigan dunes.  Conjecture is that it was always found along our beach but that is not known for sure.  We have never intentionally planted it nor seeded it; it arrived on its own with a little help from the wind. We’re happy to have it here!

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No sand berms this year

The Park District built no sand berms this year. The simple reason is that the people who knew how to run the machines, retired. In these budget constrained times, nobody was hired to replace them. Additionally, the snow fence was placed next to the sidewalk. The way snow fence works is that it creates drifts just downwind from it. That is why, in previous years, they put it in the middle of the beach. This year they followed the lead of the erosion control project and put the fence near the sidewalk. The results are big drifts on the sidewalk. All of the snow on the beach blew and didn’t stop til it hit the fence and then piled up on the other side. Better luck next year!

So, is snow a stand in for sand? Will the erosion control project pile more sand on the sidewalks? I think that it won’t. Although snow and sand both blow, sand is much heavier and slows down much faster. Someone did their thesis on how long it took a sand grain to stop, and it was 15 feet. That is the width of our erosion control strips.

Where there was some accumulation of sand in the newly planted areas, snow did slow down and not drift as much behind. Since not much new sand has collected, the snow fence is still the feature that is affecting snow deposition the most.

Future years will give us more information, and hopefully we will be proved right in our placement. In the meantime, walking is easier on the beach than the sidewalk.