The changing natural world at our doorsteps | Illustration and text by Patterson Clark
December 7, 2010
Teasel: a runaway industrial plant
Rusty brown teasel heads are standouts in December’s weedy pastures and roadsides
In the early 1700s teasel was brought to the United States from Europe and grown for its seed heads, or combs, which were tied onto frames and brushed across woolen fabric to "tease," or raise a nap on, the cloth.
The comb's flexible spiny bracts were ideal for the task. As late as the mid-20th century, teasel combs were still clustered onto rotating drums in textile mills. Wire brushes now do the job.
These days, teasel raises only the ire of land managers, who consider teasel an invasive plant that can outcompete native vegetation. Three species of teasel now range from coast to coast.
Seeds germinate easily in sunny, poorly drained soil. The plant's first year is spent as a deepening taproot that feeds a large rosette of leaves. In the spring of its second and final year, teasel sends up a flower stalk topped with a bristly green head encircled by a ring of small pink flowers. By the first week of December, the seed head will have dropped as many as 2,000 seeds, most landing within five feet of the plant.
Studying possible biological control of the weed, scientists have identified more than 100 organisms that prey on teasel in its native Eurasian range.
A mite, a flea beetle, a leaf-mining fly and a sawfly show the most promise for keeping teasel under control. Those arthropods first need to go through a battery of studies, some under quarantine to make sure they won't attack any crops or plants native to North America.
"The teasel biological control program has been underway for about seven years," says USDA entomologist Brian G. Rector. It may be several more years before a teasel predator is released. "It's rare that a single agent acts as a 'silver bullet,'" says Rector, so more than one bug may be needed to do the job.
An industrial teasel gig is displayed in Britain's Trowbridge Museum, where visitors can study the history of woolen cloth production. (Photo from Trowbridge Museum)