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Invasive Tumbleweeds in Orange County

Salsola tragus, commonly known as Russian thistle, is an invasive tumbleweed that can be found in a variety of habitats in Orange County. What makes this tumbleweed particularly problematic is its exceptional ability to disperse seeds with the help of the wind, water, and human beings after the plant itself has already died. Russian thistle is so good at spreading its seeds throughout disturbed habitats that it invades and outcompetes native vegetation. Not only that, when the plant has died and is ready to disperse its seeds, its sharp thorns are powerful enough to total a car if it ends up blowing onto the road. Russian thistle is also excellent at harboring pests like the beet leaf-hopper, or Circulifer tenellus, which negatively impacts agriculture.

Russian thistle, specifically the Salsola tragus species, is originally from Russia and China, and its seeds were unintentionally brought to the state of South Dakota in 1873 by Russian immigrants. From there, Salsola tragus was able to successfully spread to every single state by 1895 via wind or by contaminating railroad cars. Today in Orange County, Russian thistle tends to be found in disturbed habitats, but it can be found in all types of habitats. There are a few species of Russian thistle that can be found in Orange County.

Photo Credit: Heath McAllister

Salsola tragus is particularly known for its tumbling behavior when dispersing its seeds. When it's young, the leaves are dark green, and the bush itself can grow up to 4 feet long in diameter. It grows spines along its stems to prevent being eaten before it is able to reach maturity. After it dies, the stem breaks off and is able to tumble away, which helps the seeds fall off and disperse to various locations. This variety typically spreads its seeds between late fall and early winter.

Photo Credit: Gary McDonald

Another variety that can be found in Orange County is Salsola australis, which typically does not tumble and relies on the wind to disperse its seeds by blowing it directly off the plant. Native to South America and Australia, this variety is smaller than Salsola tragus and usually does not grow bigger than 2 feet long in diameter. It arrived in the United States in the early 1900s, and typically disperses its seeds in late summer. Even though this variety is not from Russia, it is also called Russian thistle

Photo Credit: Shana Welles

Salosa ryanii is a hybrid tumbleweed of Salsola australis and Salsola tragus, but it is not typically found in Orange County. It’s important to note that this variety can grow twice as large as the other two species, being able to grow 6 feet tall; it’s much more aggressive than its parent species and has the potential to spread to Orange County from other areas like Riverside where it is already invading. This species was first documented in 2002.

Russian Thistle can be dealt with by manually removing it and disposing of it in the trash or landfill. The Salsola tragus and Salsola australis species are rather lightweight, and the plant can easily be pulled off of the ground. Its spines are incredibly sharp, however, and once it's removed from the ground, its seeds drop everywhere, so if you do happen to remove Russian thistle by hand, it's important to be careful about where the seeds are dropping so that they can be picked up and all transferred into the trash. If you don’t want to throw them away, Salsola tragus is entirely edible to humans as well. If you’re interested in making a difference and helping control the invasion of tumbleweeds in Orange County, join us in our restoration events by signing up through our EventBrite page! Our restoration events involve removing invasive species, including Russian Thistle at the Huntington Beach Wetlands Conservancy, and they’re free to join!

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