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  • Ash, Lead Naturalist

Native, Invasive and Poisonous Plants!

Updated: Sep 23

Written By: Ashley Goldbeck

Introduction:

Have you ever taken a hike at Willow River or Kinnickinnic State Park and stumbled across a beautiful wildflower or strange plant and wondered what it was? Or maybe you finished a hike through the prairie or along the river only to find you have obtained a nasty itch, burn or blister on your skin? Here at Willow River State Park, we have a variety of beautiful wild flowers. We also have a lot of poisonous and invasive plants to watch out for as well! While hiking along any park trail it is always beneficial to bring along a Wisconsin wildflower guide or sketch paper so you can document any new unidentifiable plants to research later. Another good rule of thumb; never touch any plants you are unable to positively identify! You never know what kind of tricks some plants may have up their stems, or worse, how much poison! In this article, I will share with you some fascinating facts and photos of several plants within the park. With new species constantly popping up or blooming bi-annually, some of the plants you come across will vary by season, and certainly each year so note that this list is not complete. Last but not least, always be sure to share any sighting you find with us. We love hearing from you!


Make it A Family Adventure!

Get out and explore these locations together as a family! Bring some sketch paper, field guides and a camera. If hiking to these locations with little ones here are some great interactive questions to get their wheels spinning: 

  • What is your favorite wildflower? 

  • Can some wildflowers grow in snow?

  • What does native mean?

  • What does invasive mean?

  • Just because a flower is non-native does that mean it is invasive?

  • What is the difference between an annual, bi-annual and perennial plant?

  • Can native wildflowers become invasive?

Using the map above to help you navigate, let's see how many plants you can find! Below is a list of various species which can be found here at Willow River State Park. For each plant listed, I provide some background information, and uncover which trail(s) it can be found on!


CROWN VETCH: INVASIVE

CROWN VETCH
  • Blooms in the summer

  • Non-native perennial 

  • Likes dry, sunny, open fields or roadsides 

  • Originally planted to stop erosion from road construction, can also pull nitrogen from air and filter it into the soil to improve soil fertility

Can be seen on: Purple Trout Brook Trail, Gray Nelson Farm Trail


LEAFY SPURGE: INVASIVE/POISONOUS

  • Narrow lance shaped leaves that ooze milky sap when broken or rubbed against 

  • Blooms in the spring and summer

  • Likes dry, sunny open fields or roadsides with disturbed soils

  • Aggressive European import, considered a noxious weed in Wisconsin. Special beetles are being released to eat in an attempt to control aggressive growth. This plant is poisonous. Will burn or blister skin on contact. Deadly to humans and animals if large amounts are ingested. 

  • Can be seen: Throughout the park


DAISY FLEABANE:

DAISY FLEABANE
  • Blooms in spring, summer and fall 

  • Native annual 

  • Likes both wet and dry, sunny or shady climates, and old fields

  • One of the first flowers to bloom in spring and last through fall, if dried are believed to keep away fleas

Can be seen on: Purple Trout Brook Trail, Gray Nelson Farm Trail, Pink Burkhardt Trail



BLACK-EYED SUSAN:

BLACK-EYED SUSAN
  • Blooms in summer and fall 

  • Native perennial

  • Likes prairies, fields or dry open deciduous forests

  • The seeds are a great food source for gold and House finches

Can be seen on:Purple Trout Brook Trail, Gray Nelson Farm Trail, Red Whitetail Trail, Orange Knapweed Trail, Yellow Pioneer Trail, Pink Burkhardt Trail



MILKWEED: POISONOUS

MILKWEED
  • Blooms in the summer

  • Native perennial 

  • Likes wet or dry, sunny or shady fields

  • There are over 2,000 types of milkweed plants. The plant's milky sap contains cardiac glycosides which causes hot flashes, rapid heartbeat and weakness. Monarch butterflies lay their eggs and feed exclusively on milkweeds, with no ill effect and become poisonous themselves to predatory birds. 

  • Can be seen: Throughout the park


COMMON YARROW:

COMMON YARROW
  • Fernlike feathery leaves

  • Blooms in the summer and fall

  • Native perennial 

  • Dry and sunny deciduous woods, fields or prairies

  • Many cultures have used it as a medicinal herb, and during the Trojan War it was used to stop bleeding due to its coagulating abilities!

Can be seen on:Purple Trout Brook Trail, Gray Nelson Farm Trail, Red Whitetail Trail, Orange Knapweed Trail, Yellow Pioneer Trail, Pink Burkhardt Trail



WHITE CLOVER: INVASIVE

WHITE CLOVER
  • Blooms in spring, summer and fall

  • Non-native perennial 

  • Likes dry and sunny lawns and fields

  • Known for its creeping, ground cover habits,

  • Very attractive to several butterfly species such as skippers, blues, sulphures, and hairstreaks

  • Can be seen: Throughout the park


ANEMONE(S):

  • Blooms in spring and summer

  • Native perennial

  • Likes wet meadows and prairies

  • Also called windflower due to its tendency to flap delightfully in the breeze, sometimes grown as a garden flower because of its beautiful appearance

  • Can be seen on: Purple Trout Brook Trail, Brown Oak Ridge Trail



WILD PARSNIP: INVASIVE/POISONOUS

  • Blooms in spring and summer

  • Likes wet, sunny fields and roadsides

  • Skin will blister and weep when exposed to sunlight after touching this plant!

  • A host to the black swallowtail butterfly caterpillar

  • Can be seen: Throughout the park


HOARY PUCCOON:

  • Bloom in spring only

  • Native perennial

  • Likes dry and sunny rocky soils, prairies and roadsides

  • Puccoon is a native name for plants used for color dye, roots of this flower make a red dye, Looks similar to butterfly weed

  • Can be seen on: Purple Trout Brook Trail


WHITE CAMPION:

  • Blooms in summer

  • Non-native annual

  • Likes dry fields, gardens, roadsides and disturbed soils

  • This is an evening blooming plant that attracts night-flying insects like moths, and the seeds it drops in winter are good food for finches and sparrows

  • Can be seen on: Purple Trout Brook Trail


OX-EYE DAISY:

  • Blooms in spring and summer

  • Non-native perennial

  • Like wet or dry sunny fields, along roads or pastures

  • Contains Pyrethrum a chemical that repels insects so it is often used in organic pesticides

  • Can be seen: Throughout the park


BIRDS-FOOT TREFOIL: INVASIVE

  • Non-native perennial

  • Blooms in spring, summer and fall

  • Likes dry sunny old fields and roadsides

  • Widely planted for erosion control, can take over disturbed soils quickly, its seeds look like a birds foot hence the name and the nectar is a butterfly attractant

  • Can be seen: Along park roads and along parking lots


YELLOW WOOD SORREL:

  • Blooms in spring, summer and fall

  • Annual native

  • Likes dry, sun disturbed soils, gardens and roadsides

  • Because of a high concentrations of vitamin C, phosphorus and potassium it has been used as a folk medicine to treat many ailments

  • Can be seen throughout the park


GOATS BEARD:

  • Blooms in spring and summer

  • Non-native biennial

  • Likes dry sunny fields and roadsides

  • Turns to face the sun and opens only on sunny mornings and closes back up by noon, the taproots can be dug and roasted as a coffee substitute

  • Can be seen on: Purple Trout Brook Trail, Gray Nelson Farm Trail



GARLIC MUSTARD: INVASIVE

  • Heart shaped lower leaves with upper leaves all smelling of garlic

  • Blooms in spring and summer

  • Biennial non-native

  • Likes wet shady deciduous woods

  • Leaves used to be cultivated for salads black seeds can be used as pepper substitute now considered a noxious weed in Wisconsin

  • Can be seen: Throughout the park.


WATER HEMLOCK: POISONOUS

  • Blooms in the summer and fall

  • Native perennial

  • Likes wet sunny ditches, meadows, roadsides, and river banks

  • This is by far the most poisonous plant in Wisconsin. The taproots smell like carrots but ingesting a small amount will lead to convulsions and death by paralysis of the lungs.

  • Can be seen along the river on the Purple Trout Brook Trail


PURPLE CONE FLOWER:

  • Blooms in summer and fall

  • Native perennial

  • Likes dry, sunny prairies, roadsides and ditches

  • Popular flower for herbal remedies, American goldfinch loves to eat the seeds and many butterflies sip its nectar

  • Can be seen: Near Nature Center and on Purple Trout Brook Trail


WOOD NETTLE:

  • Large green leaved plant with leaves alternating on the stem, often confused with stinging nettle where the leaves are opposite on the stem

  • Blooms in spring, summer and fall

  • Likely found growing on forest floors

  • Native perennial

  • Although the hairs on the stems and undersides of the leaves are known for giving people a nasty sting touched this plant is prized by foragers for its food and medicinal purposes

  • Can be seen: Purple Trout Brook Trail, Brown Oak Ridge Trail, Gray Nelson Farm Trail, Pink Burkhart Trail


GOLDEN ALEXANDER’S:

  • Blooms in the spring

  • Native Perennial

  • Likes wet, sunny ditches along roadsides and fields and woods

  • Related and often mistaken with wild parsley or water hemlock due to similar color or globe-like clusters, both of which are poisonous. But Golden Alexander’s was once used to heal wounds, and relieve fevers and syphilis.

  • Can be seen: Throughout the park


WILD LUPINE:

  • Likes sunny, well-drained and slightly acidic soils

  • Blooms late spring and early summer

  • Native Perennial

  • The only host plant for the endangered Karner Blue Butterfly caterpillar

  • Can be seen: Near Park Office and Nature Center


WILD STRAWBERRY:

  • Blooms in spring

  • Native perennial

  • Likes dry, sunny edges of woods

  • Produce the sweetest tasting naturally produced berries in WI

  • Can be seen on: Purple Trout Brook Trail, Brown Oak Ridge Trail, Gray Nelson Farm Trail, Pink Burkhart Trail, Mounds Trail



GROUND IVY: INVASIVE


  • Non-native perennial

  • Likes dry and shady disturbed lawns

  • Not an ivy but a Eurasian import from the mint family. Crush leaves to smell and identify. Once used to ferment and flavor beer. Can overcome lawns quickly.

  • Can be seen along several park trails


WINTER CRESS:

  • Blooms in the spring & fall

  • Non-native biennial

  • Likes wet, sunny, open fields along roads or train tracks

  • One of the first flowers to bloom in spring, often with snow still on the ground, hence its name. Important food source in early spring for deer. Seeds are hot and used as a peppery substitute. Has been used to treat wounds in folk medicine.

  • Can be seen throughout the park


COMMON MULLEIN:

  • Blooms in summer and fall

  • Non-native Biennial

  • Likes dry sunny fields along roads

  • The first year it grows as a short velvety plant the second it shoots up on the stalk. Was one used as a torch by romans, in footwear for warmth and comfort by Native Americans

  • Can be seen on: Yellow, Orange, Red, Purple, and Silver trails and growing near parking lots


Additional Plants to be Added:

Hoary Asylum, Yellow Avens, Tall Meadow Rue, Deptford Pink, Coreopsis, Common Self Heal "Heal-All", Marsh Hedge Nettle, Thimbleweed, Sweet Clover, Enchanters Nightshade, Bloodroot, Turtlehead, Pineapple weed, Wild Bergamot "Bee Balm", Prairie Blazing Star, Spotted Knapweed, Posion Ivy, Big Blue Stem, Prairie Drop Seed, Smooth Brome Grass, Bitter cress, False Sunflower, Hare’s Foot Clover, Wild Quinine, Timothy, Tick Tre-foil, Swamp Milkweed, White Sagebrush, Red Top Bent Grass, Chickweed, Switch Grass, Alum root, Hepatica, Aster, Phlox, Dame’s Rocket, Plantain, Rattlesnake Master, Prairie Smoke, Queen Anne’s Lace, Raspberry, St. Johns Wort, Sage, Skunk Cabbage, Wood Violet, Solomon’s Seal, Hoary Vervain, Ginseng, Goldenrod, Hawkweed, Honeysuckle, Jack in the Pulpit, Joe Pye Weed, Jimsom weed, False Blue Indigo, Lobelia, Boneset, Compass Plant, Columbine, Culvers Root, mustard, Motherwort, parsnip, Spiderwort, sumac, Toadflax, Speedwell, Verbena, Shepherd’s Purse, ragweed, sneezeweed, yarrow, etc.


What plants did you find on your adventure? Share your favorite findings with us! We love hearing from you!


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