6021 Development Drive, Suite 2, Charleston, IL 61920 info@colescountyswcd.org 217-345-3901 ext. 3

Teasel: A Rapidly Spreading Threat

As you travel along Illinois highways this time of the year, you may have seen a tall, spiny plant with big purple or white flowers. You might have even considered taking some seed or seed heads home to plant and use as an accent flower or for use in dried flower arrangements. PLEASE DON’T!! This invasive weed is spreading into our parks, public lands, pastures and open woodlands.

Flowers of the Fuller’s Teasel (Dipsacus fullonum), Ottawa, Ontario, Canada

As noted by the Illinois Natural History Survey, this plant is a danger to our natural areas. “Teasel is an aggressive exotic species that has the capacity to take over prairies and savannas if it is allowed to become established. Lack of natural enemies allows teasel to proliferate. If left unchecked, teasel quickly can form large monocultures excluding all native vegetation.” As a reminder, control of invasive species like teasel is required in acreage enrolled in programs such as CRP.

Teasel species produce large numbers of seeds and can easily colonize areas, displacing native plants. When a mature teasel plant dies it leaves a large dead area from its basal leaves, which becomes the nursery site for new seeds shed by the plant. Seeds have the capacity to be water-dispersed, which may allow seeds to be dispersed over longer distances by flooding. Immature seed heads of teasel are capable of producing viable seed, so simply mowing the infested areas can do more harm than good—increasing the spread of the plant. In fact, seeds clinging to roadside mowers is one of the ways the plant has spread so rapidly in Illinois. According to the Illinois Natural History Survey, the “rapid range expansion (of these invasive plants) probably was aided by construction of the interstate highway system.”

Two teasel species are found in Illinois: common teasel and cut-leaved teasel. Common teasel blooms from June through October (pink or purple flowers), while cut-leaved teasel usually blooms July through September (white flowers). The unique flowers make teasel readily identifiable when blooming.

Please help stop the spread of teasel in our area. Management of teasel includes removing existing plants to prevent seed dispersion. Plants can be dug up and disposed of or several herbicides can be effective if plants are sprayed before flower initiation. For recommendations on controlling teasel on your land, please visit the Illinois Natural History Survey – Teasel website for more information. https://www.inhs.illinois.edu/research/vmg/teasel/