Southwest Plants: Tumbleweeds
19 Southwest Highways & Fields
The seeds are unusual in that they contain a coiled embryonic plant surrounded by a very thin membrane. They can remain viable for a long time, are fire-resistant, and can germinate at a wide range of temperatures. They are ready to root immediately upon uncoiling, so the embryo can begin a new seedling very quickly, and in the spring the seedlings produce tender, long, needle-like leaves that are edible. As the plant grows larger the first leaves are replaced by oval, spiny leaves which are not palatable, at which time the plant has reddish-purple striping. The plant is multi-branched and rounded in form, with flowers that grow at the ends of spiny bracts at the base of the leaves. S. collina is the smaller species, usually only 3-4 feet tall, while S. tragus can get up to 6 feet tall. In the Fall the leaves drop, leaving a woody sphere covered in seeds. Special tissues in the base of the stem separate, allowing the plant to be blown away by the wind. As it rolls over open fields, it drops its seeds. Depending on the size and species, they can have as many as 250,000 or even a million seeds per plant.
Tumbleweeds Against a Fence
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only 3-4 feet tall, while S. tragus can get up to 6 feet tall. In the Fall the leaves drop, leaving a woody sphere covered in seeds. Special tissues in the base of the stem separate, allowing the plant to be blown away by the wind. As it rolls over open fields, it drops its seeds. Depending on the size and species, they can have as many as 250,000 or even a million seeds per plant. As is often the case, the damage caused by tumbleweeds is really the fault of us humans. Tumbleweeds need disturbed ground to germinate, because they do not compete well with other plants. We are constantly disturbing the earth by digging, scraping, bulldozing, tilling, mowing, and killing off plants, creating environments ideal for more tumbleweeds. If not for us, there would be less disturbed ground and the tumbleweeds would be controlled. Tumbleweeds can only tumble if there are no obstructions. So first of all we have created vast expanses of flat, open cropland for them to roll across, whereas previously the tall grasses of the prairies would have kept them from tumbling very far. Secondly, we have fenced in sections of our vast expanses, creating the only obstacle that stops them. Then we complain that the tumbleweeds prevent access to the fence for repairs and short out electric fences during ice storms and provide habitat for rattlesnakes. Tumbleweeds, like all woody plants, can catch and spread fire, but since we are often the source of the fire and we have made it easy for burning tumbleweeds to roll around spreading the fire, we need to take some of the responsibility. Tumbleweeds are also blamed for causing traffic accidents and scraping the paint off of cars, but how is a plant to blame for us using cars in the first place and getting in their way?