Clouds of dust blowing in the wind. The cracked desert ground. A cow’s skull on a rock. After one long whistle, the camera pans to show the subtly dangerous threat on the western horizon.
The Tumbleweed.
Tumbleweeds (or Salsola tragus), despite being a hallmark of the western movie, are not native to the United States. Believed to have been accidentally imported from Russia in a batch of flaxseed in 1870 (and later spreading across the country along the railways), the plant poses several threats to the people and land they blow around.
Their life cycles begin as Russian thistle plants, large green bushes that take root in loose soil. The plants once dried out, become uprooted by strong gusts of wind and tumble (hence the name) around the area. Once loose in the wind, the tumbleweeds distribute more thistle seeds around the area, and while most are unable to root, many grow into new bushes, beginning the cycle anew.
Its flammability, especially in desert biomes, has led to laws and regulations to prevent wildfires. The South Coast Air Quality Management District (AQMD) has a phone number to call in case anyone has to burn the weeds, permits, and inspections to obtain, and then further rules about the tumbleweeds that can be burned. These rules help maintain the public’s health, limiting smoke in the air.
When they clump up, which is easy for them to do, they cause major inconveniences or even dangers. They can block waterways, such as along the California Aqueduct, where they are gathered in piles and sent to specific burn piles to avoid becoming fire hazards (in a state already prone to fires). An article by Reuters describes how they can collect in large, troublesome piles, blocking access to homes or cars. Their thorny exteriors make it easy for them to clump together and difficult to remove them. On highways, they can block traffic or cause drivers to swerve out of the way.
In farmlands, tumbleweeds pose even more threats. As the seeds spread root in loose soil, many can take root in soil intended to plant crops. Before they’re uprooted agricultural pests such as the beet leafhopper can shelter inside them and lay eggs.
The clumped weeds posed much more than an inconvenience to Clovis, New Mexico, in 2014, when they blocked exits to multiple peoples’ houses. Volunteers from the local air force and members of the Public Works Department cleared the houses.
This was not the only time local governments were forced to act against the weeds. When the weeds end up in the street, it is the government’s responsibility to pay to remove them, but otherwise, homeowners have to pay. Private contractors can cost hundreds of dollars, but otherwise, removal is difficult.
For people, the main danger is allergies. The plant can cause common allergic responses, similar to other pollen allergies, but touching it directly can cause dermatitis, a skin irritation.
People in areas with tumbleweeds should avoid loosening soil, as distributed thistle seeds might take root in the ground. When handling them, people should take precautions by wearing gloves and not touching them directly.
But the regular Russian thistle isn’t all that Americans have to worry about; A new hybrid species, Salsola ryanii formed from the Salsola tragus and Salsola australis, has persisted despite early predictions that it would die out. It grows larger than its parents, up to about six feet in diameter. It rapidly tumbled through California, and according to the University of California’s Agriculture and Natural Resources Division, the overlap between the two parents’ ranges means it’s highly likely that more of the bigger hybrids will come about.
Despite their dangers, tumbleweeds are deeply ingrained in American culture. From appearances in Western movies to being used as a way to reference people-less parts of the West, some have found ways to make the most out of the dastardly plant.
As discussed in an NPR article from 2007, they’ve brought profit in unexpected places. Linda Katz began a tumbleweed-selling website as a joke, but orders started coming from Hollywood prop orderers, including the Barney TV show and NASA.
The plants are also edible. Various livestock can munch on them, though not in too great a quantity, and not once they’re overly matured, as either can be poisonous to the consumer. This came in handy during the dust bowl when little hay was available. People can eat weeds during the first stage of its life. Several gardening blogs, such as Foodie Gardener, have recipes for eating the plant before the wind uproots it.
But most people have decided their town isn’t big enough for them both. Common herbicides can kill the seeds if used before they grow, but like many weeds when the same herbicide is introduced in the same area, they may evolve and become resistant. According to a study from 2017, the Salsola tragus variety is developing resistance to glyphosate, the most common herbicide.
Other methods of elimination have been tested, to no avail. In 2014, the Agricultural Research Service’s Foreign Disease-Weed Science Research Unit was searching for fungi that would spread diseases to the plant. According to a publication from the United States Department of Agriculture, in the 1970s, two species of moths were released as biocontrols, but did no damage, thriving on the weeds instead.
While the threat of tumbleweeds looms large, it is worth remembering that they are far from the only invasive in the United States wreaking havoc on agriculture. The spotted lanternfly, for example, feeds on sap from trees, stressing their health. The numerous species of invasive carp can outfeed local populations, negatively affecting the fishing industry.
With invasive species, the best thing to do is prevent the invasion in the first place. Educating the public and tracking their movements and resistances is also vital, such as in the case of the European Grapevine Moth, which was eradicated in the United States through coordination on every level, including the general public and stakeholders involved in the wine industry. It will take similar coordination on each level to eradicate the tumbleweed for good. Until then, it will continue to tumble off into the sunset.
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