Photo by D. Rowlands, Flickr
In the second week of January, I was standing outside of a dental office on the south edge of Greeley trying to figure out, quite frankly, how I could avoid going in. Because of the pandemic, I had skipped my regular, six-month dental checkup last summer, and because of the move to Greeley, I had had to find a new dentist to replace the one that I had been going to in Pennsylvania for the past 34 years! Dental visits were never a favorite part of my health-maintenance regime, but I always tried to be an adult about it. This new office, though, picked at random from the lists of dentists in Greeley looked too fancy, too upscale for me (and, it turns out, I was right! But, that’s a different story for a different time and place!).
Anyway, I was standing out in the cold January morning. The sun was shining but not yet warming anything up, and the wind was blowing hard from the northwest. When all of a sudden a tumbleweed blasted by and triggered a very deep, very old memory cascade!
I saw my first tumbleweed back at Texas Tech in Lubbock at the end of my first freshman semester (probably November, 1970). I had been in Lubbock for three months and had gotten used to the dry air of West Texas (a very big change from the steamy humidity of Houston!) and also to the almost constantly blowing wind with its nose-clogging and eye-irritating load of fine sand and grit. There was, though, one more level of indoctrination that I had to go through to really become a West Texan. And, it happened that morning while I was walking to my 9 am calculus class. I looked up from my sleepy walk and was quite surprised to see the windward side of the Biology Building covered with a tangled pile of tumbleweeds almost up to its second story windows.
I stood, amazed, in the cold, morning air as one after another, rolling, gray-brown tumbleweed, each about a foot and half in diameter, rocketed across the open spaces and parking lots of the campus and sunk themselves into the growing mass next to the building. A few of the weeds slipped out of the grip of the catch-pile and continued around the corner of the building. I saw one crash into a student who was walking, unawares on the sidewalk. She kicked the tumbleweed out of her way and kept on going. She must have been a local or, at least, an upperclassman. Tumbleweeds did not have any cache or mystery for her!
Photo by D. Jandyw.com, Flickr
The tumbleweed! A symbol of the vast spaces and isolating loneliness of the west! A metaphor for the rugged individuals that settled the frontier, the iconoclasts that were blown across the landscape of our country by the wind and fates. The movie “The Big Lebowski” opens with an extended scene of a tumbleweed moving across the open, dry plains and into the cityscape of humans while the “Tumbling Tumbleweeds” song plays and Sam Eliot narrates. The images foreshadowed “The Dude” as an aimless, drifting human-tumbleweed in a bathrobe with a pitcher full of White Russians and the rug that “really tied the room together” (click here for a look at this incredible opening sequence)!
This iconic symbol of the American West, though, is a relatively recent invader from the steppes of Russia! Gene Autry and Roy Rogers and all of the Sons of the Pioneers should have dressed up like Cossacks when they sang about them!
A ”tumble weed” is an annual plant that, as part of its seasonal senescence, detaches either all or part of its above ground biomass from its anchoring roots. This then allows its stems and branches and dried, seed-filled flowers to roll across a sometimes considerable stretch of landscape. The purpose of this detachment and “tumbling” is, of course, the dispersal of seeds. Ecosystems like arid grasslands, prairies and steppes that have regular winds and few biological or physical obstructions are most likely to have tumbleweeds.
Seed dispersal via plant tumbling is a fairly unusual plant strategy. Most plants spread their seeds either via gravity and chance or via modifications in seeds to allow wind dispersal (like dandelion seeds or maple tree samaras), or water dispersal (like palm trees or mangroves). Plants also utilize a variety of animal assisted seed dispersal mechanisms. Some of these are “epizoochoric” (a sticky or spiny seed gets attached to the outside of an animal), while many others are “endozoochoric” (a seed inside of an edible fruit passes through an animal’s digestive track and is deposited (often along with a dab of fertilizer!) at some distant location).
Many different kinds of plants around the world make tumbleweeds. In North America, though, the major “tumble-weeding” plant species is Salsola tragus (whose species name was revised for a short time to Kali tragus but has since reverted back to S. tragus). This is a Ukrainian and western Russian plant that is called, among several other common names, “Russian thistle” (although it is not really a thistle).
Green Russian thistle, Photo by M. Lavin, Flickr
Russian thistle was transported to North America in a shipment of flax seeds back in the early 1870’s. These thistle seeds germinated and matured in the flax fields of South Dakota and then rapidly spread across the continent. This spread was accomplished not only by the very efficient, long-distance tumbling of the dried plants (each Russian thistle plant contains approximately 250,000 seeds!) but also via transported agricultural equipment and train cars (especially livestock cars). By 1895, Russian thistle had reached California. It can now can be found in every state in the country with the exception of Alaska and Florida. Over 100 million acres of land all across the United States contains Russian thistle.
The seeds in a Russian thistle lack both protective coverings and stores of nutritional energy. They cannot germinate until moistened by spring rains and warmed by rising spring temperatures. The initial shoots are grass-like with long, double, green leaves supported on red or purple stems. These initial leaves are quite palatable and can be eaten by both wild and domesticated grazing animals.
Photo by J. Reis, Wikimedia Commons
As the plant matures into summer, though, it takes on a rounded, bushy shape and produces a large number of small ,white, yellow or pink flowers. The flowers are protected by surrounding thorny leaves which greatly discourage active browsing of the plant. In late fall, an abscission layer forms at the base of the dried plant and the entire above-ground biomass then is free to move in whatever direction the wind is blowing, dropping its seeds along the way.
As a weed, Russian thistle steals moisture from native plants and from crop plants in soil ecosystems that are typically critically short of water. In wheat fields, each Russian thistle plant takes up 44 gallons of water during a growing season. On uncultivated dry grasslands or in disturbed areas of these dry soil systems its annual water consumption may even be higher.
Photo by D. Updegrade, USAF
The dry, above ground plant mass of Russian thistle is extremely flammable, and as it accumulates in sheltered areas of a dry ecosystem it can serve as a rapidly burning fuel for wildfires. Blowing tumbleweeds (which can be as large as small cars!) can also interfere with car and truck traffic and can cause accidents via direct collisions and even build up in such great masses so as to block highways.
Russian thistle is also a refuge and reproduction site for the beet leafhopper which is the only known insect vector that transmits the beet curly top virus (BCTV). This plant virus can affect not only beets but also a wide range of other important crops (including tomatoes, peppers, squash, spinach, cantaloupes, watermelons, beans and cucumbers). Control of BCTV is not possible without control of Russian thistle!
So, watching the tumbling tumbleweeds rolling across the landscape, what should we think about? The Old West and all of its mythologies? Or, the damaged, homogenized ecosystems of our Anthropocene?