Common teasel in bloom. The flowerheads of teasel species are distinct, unusually large, stiff and sturdy. / Photo Credit: Steve Dewey, Utah State University, Bugwood.org

By Erika Segerson-Mueller, DNR Invasive Plant Program Specialist, Oshkosh Service Center
Erika.SegersonMueller@wisconsin.gov or 715-492-0391

Two species of teasel are present in Wisconsin: common teasel (Dipsacus fullonum) and cut-leaved teasel (Dipsacus lacinatus). Although they are known today as invasive plants, their Latin names speak to a useful history.

The species name of common teasel (fullonum) comes from “to full,” a step in woolen clothmaking that involves using water and agitation. Teasels, native to Europe, were introduced to North America in the 1700s to be used in this manner by textile processors. The stiff and sturdy flower heads of teasel were used to comb the surface of damp cloth to give it a fluffier finish. Continue reading “Teasing Out Invasive Teasels” →

By Erika Segerson-Mueller, DNR Invasive Plant Program Specialist, Oshkosh Service Center;
Erika.SegersonMueller@wisconsin.gov or 715-492-0391

With 145 invasive plants regulated under Wisconsin’s Invasive Species Rule NR40, it can be challenging to identify some of these plants while out in the woods.

The task can be further complicated by the presence of native lookalikes, plants that appear very similar to harmful invasive species but benefit wildlife, pollinators and ecosystems in Wisconsin.

Continue reading “Invasives And Imposters: Native Lookalikes To Know (Part 1)” →

By Erika Segerson-Mueller, DNR invasive plant program specialist, Oshkosh;
Erika.SegersonMueller@wisconsin.gov or 715-492-0391

The white milky sap of spurge plants, sometimes called “wolf’s milk,” can be toxic to cattle and irritating to human skin. / Photo Credit: Norman E. Rees, USDA Agricultural Research Service Retired, Bugwood.org

Managing invasive plant species can really be a pain. When the plants you are targeting can potentially harm human health, that pain can become quite literal.

Leafy spurge (Euphorbia esula) and Cypress spurge (Euphorbia cyparissias) are restricted invasive plants under Wisconsin’s Invasive Species Rule NR40. Aside from their tendency to spread aggressively and displace native species, both plants contain a white milky sap that can cause skin irritation in some humans and is potentially toxic to cattle and horses. Continue reading “The Scourge Of Spurge, Both Cypress And Leafy” →

By Erika Segerson-Mueller, DNR Invasive Plant Program Specialist, Oshkosh Service Center;
Erika.SegersonMueller@wisconsin.gov or 715-492-0391

Leaves appear wrinkled and less healthy in garlic mustard plants affected by aphids. / Photo Credit: Rebecah Troutman, Holden Forests and Gardens, Bugwood.org

The NR40-restricted invasive plant garlic mustard (Alliaria petiolata) is prevalent in many Wisconsin woodlands, but a new wave of hope is on the horizon.

The garlic mustard aphid, a tiny, dark, gray-to-green insect sometimes called the “grenade” aphid after the pattern of raised blotches on its back, was found in 2021 at the Holden Arboretum in Ohio. It could become a viable form of biocontrol for the garlic mustard plant.

Continue reading “Dropping The Aphid Grenade On Garlic Mustard” →