You know the scene—the one from the old Western where a sole tumbleweed rolls across the desert vista, representing the wide open spaces of the American West … or comes to rest at the abandoned ranch as a symbol of desolation …
Some of us aren’t so fond of this iconic but spiny and invasive film star. But it does have an interesting story. And perhaps, in the narrative of the New West, this irritating character isn’t all bad?
The name “tumbleweed” refers to a strategy rather than a particular botanical species. Plants in this group grow into massive flower clusters, sometimes 6 feet across. In fall, the big round bundles die, dry out, and break off at the base, leaving a living root behind. Then they’re blown across the landscape by the wind, shedding seeds as they bounce across roads, pastures, and neighborhoods.
Since one plant can produce as many as 250,000 seeds, it’s been a highly effective dispersal method. Native to Eurasia, the plant was imported to South Dakota from Russia in the late 1800s in a shipment of flax seed. It now grows throughout the West from sea level to above 8,000′.
To make the plant even more unpopular in wildfire-prone areas, the airy spherical shape that allows the seed balls to roll, also turns them into efficient fire spreaders.
And as if drought wasn’t already a challenge here in Arizona? According to this source, one Russian thistle used 44 gallons of water when out-competing a wheat plant.
Here’s something disturbing I’ve noticed this year: Our local tumbleweed, the Prickly Russian Thistle, was rare here before the 2011 Horseshoe II fire ripped through the Chiricahuas, burning 230,000 acres, including most of my land.
Now, on much of my property, it’s the dominant plant.
So, are Russian thistles totally evil? At first stab (they’re spiny enough to flatten a tire), it sure seems like it.
Yet, according the US Forest Service studies, these plants are a valuable first step in Nature’s repair system. Russian Thistle is an “initial colonizer in primary and secondary succession”—which simply means it’s the first species hardy and determined enough to move into nutrient-deficient burned areas. They dominate for two or three years. Then, starting in Year 4, they become stunted and are slowly replaced by members of the mustard family. Gradually, these pioneer plants produce enough organic material for—we hope—the re-establishment of native grasses and, eventually, shrubs and perhaps even trees.
So, maybe, as annoying as it is, the Prickly Russian Thistle doesn’t wear as black a hat as I thought.
But I’ll still be glad to see the next character in the ongoing story.