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

The slightly off-center silvery midrib of Japanese stilt grass leaves provides a key to identification. / Photo Credit: Leslie J. Merhoff, University of Connecticut, Bugwood.org

Want an advantage over your taller friends? Try propping yourself up on a pair of stilts. As its name suggests, this is precisely how Japanese stilt grass operates. It uses “stilts” (branching rootlets near its base) both as support and to sprawl over nearby plants.

Japanese stilt grass (Microstegium vimineum) is an invasive, warm-season annual grass. It grows one to three feet tall and has an aggressive, mat-like growth that creates dense patches and discourages native plants from establishing. It is also a prolific seed producer, with each plant producing up to 1,000 seeds that can easily spread over land and water during its growing season.

Continue reading “Japanese Stilt Grass An Aggressive New Invasive” →

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

With 10 thistle species present in Wisconsin, it can be tricky to determine which thistle is which. You may be tempted to control every thistle you see, assuming all types are invasive. But Wisconsin also has native thistles that provide valuable habitat and food for small birds and butterflies.

Thistles are either biennials (following a two-year life cycle) or perennials (regrowing every spring). They have lobed, spiny leaves and sometimes spiny stems. Thistles have composite flowers, with each flowerhead being composed of many tiny flowers, or florets.

Read on a for an overview of invasive thistles found in Wisconsin so you can stop wondering: Which thistle is this thistle? Continue reading “Which Thistle Is This Thistle?” →

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” →

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

A forest road is covered by a blanket of Woodland forget-me-not. / Photo Credit: Caleb Slemmons, National Ecological Observatory Network, Bugwood.org

These easy-to-grow, sweet-sounding, small blue flowers may seem appealing, but you should forget about forget-me-nots. A garden plant frequently found in mixed bouquets, forget-me-nots can easily escape the confines of a garden and spread aggressively.

There are two species regulated as invasives in Wisconsin: an Aquatic forget-me-not (Myosotis scorpiodes) and Woodland forget-me-not (Myosotis sylvatica). Both species are restricted under Wisconsin’s Invasive Species Rule NR40, so control is encouraged if they are found on your property. These species cannot be transferred, transported or introduced without a permit.

Both the aquatic and woodland species of forget-me-not bloom in early spring and can share many visual characteristics. Continue reading “Forget About Planting Forget-me-nots” →