7 Poisonous Plants to Watch Out for in Wisconsin

You should be able to recognize poisonous plants so that you can avoid them. Which ones should you be careful of in Wisconsin?

When you are camping, bicycling, or hiking in Wisconsin’s vast wilderness, you risk having contact with poisonous plants. If you touch or swallow one of these plants, it may cause skin irritation, illness, or even death. You can avoid them, reduce the amount of damage caused by exposure, and take any other required safeguards if you know the plants that might cause harm.

Here are 7 poisonous plants to watch out for in Wisconsin.

1. Wild Parsnip

Wild parsnips’ grooved and hairless stems can grow to five feet. Their little yellow blooms have a flat top and are arranged in an array from three to eight inches broad. Their seeds are wide, dark, and winged, and they have a convoluted shape and sharp teeth.

You should steer clear of handling this plant since it has the potential to inflict severe burns that last for up to 48 hours and enhance sensitivity to sunlight.

It is possible to come across wild parsnips in several habitats, such as roadside ditches, fields, pastures, and other types of disturbed ground.

a group of wild parsnip growing in the field

2. Poison Hemlock

One hazardous plant that grows throughout the United States is poison hemlock (Conium maculatum L.). The hemlock plant features purple markings on the stem and clusters of white blossoms. This plant has a maximum height of nine feet.

When any part of the plant, including the seeds, blossoms, leaves, or fruits, is consumed, hemlock poisoning occurs. This plant has poisonous alkaloids in every component that may be lethal even in small doses. Your muscles’ ability to transmit nerve impulses may be hampered by the alkaloids, which might lead to respiratory failure and death. Some individuals may get a skin response just by touching this plant.

Poison hemlock is often seen on roadsides, in waste areas, and next to fences. This plant is especially harmful to animals since it may be mixed up with plants that are safe to eat in meadows and crops. However, unless there is no other foliage or feed available for eating, animals typically avoid it due to its terrible, musty smell.

white poison hemlock found in the forest

3. Wood Nettle

The Urticaceae family includes the native, tall, perennial plant known as wood nettle. This deadly plant has medium to dark green, coarsely toothed leaves 6 inches long and 4 inches broad, making them easy to identify. Older leaves often have hairs on the lower surface, while young leaves are coated with stinging hairs.

Stinging hairs are present on both the leaves and stem of wood nettle. When in contact with the skin, the hair tips easily fracture, enabling the inside liquid to be pumped into the targeted bodily part. It is unknown what the stinging hair’s active component is. However, it differs from the closely related stinging nettle (Urtica dioica). Canada nettle hairs cause erythema, reddening, and localized perspiration in addition to regional pain and discomfort. The discomfort might last for many weeks.

The plant grows natively in lush wooded regions, woodlands, and damp river and stream bottomlands.

wood nettle plant growing in the woodlands

4. Bittersweet Nightshade

Bittersweet nightshade is a semi-woody perennial vine or shrub poisonous to humans, animals, and domesticated plants. The plant has dark green to purple-tinged leaves, and star-shaped purple blooms with stamens in noticeable yellow cones are produced from mid-May through September.

The whole plant includes solanine, the same toxin found in green potatoes and other nightshades, and dulcamara, a glycosidic, similar to atropine, one of the poisons in fatal nightshades, in terms of both structure and effects. 

The quantity of poison changes according to the development stage, soil, light, and environment. While mature berries may be dangerous, ripe fruits are often less harmful than the leaves and unripe berries.

From backyards to pastures, streams, roadsides, and abandoned areas, bittersweet nightshades are prevalent.

bittersweet nightshade found in the streams

5. Poison Ivy

Poison ivy may spread along the ground, climb low shrubs, trees, or poles, or grow as a shrub. Each leaf contains three leaflets, each having a smooth, toothed, or shiny edge. The springtime leaves are reddish, the summertime foliage is green, and the fall time leaves are yellow, orange, or red. The shrub may also produce greenish-white blossoms and whitish-yellow berries.

These plants’ oily sap, urushiol, causes an irritating, itching allergic response. An itchy rash develops when you come into physical contact with this plant. This rash is a manifestation of allergic contact dermatitis. Those susceptible to poison ivy should take caution when burning brush piles that may have the plant in them. Breathing in the smoke from burning poison ivy can irritate the lungs.

Poison ivy may be found throughout the United States in yards, marshes, open spaces, parks, and woodland places.

poison ivy growing underneath the trees

6. Jimsonweed

Jimsonweed is an annual herbaceous plant of the nightshade family, often known as thorn apple or devil’s snare (Solanaceae). The plant produces big spiky capsule fruits frequently referred to as thorn apples and has large white or violet trumpet-shaped blooms. The simple, alternating leaves have serrated to lobed edges and are carried on the green, sometimes purple-tinged stalks.

Hyoscyamine and hyoscine are two potent alkaloids found in the leaves, and the whole plant is toxic if consumed. Jimsonweed is often found along roadsides or other disturbed environments. It may reach 1 to nearly 2 meters (up to 6.5 feet).

three white jimsonweed growing along the roadsides

7. Stinging Nettle

Herbaceous stinging nettles can grow to 6½ feet. The plant’s golden spreading rhizomes allow it to grow vegetatively, and it generally produces dense colonies. The serrated leaves grow in opposing orientations along the stem. They are coated in a thick layer of stinging and non-stinging trichomes (plant hairs).

The stinging trichomes on the leaves and stems shed their bulbous caps when touched, exposing their needle-like tubes that pierce the skin. Acetylcholine, formic acid, histamine, and serotonin are some of the chemicals found in this plant. In humans and other animals, they may result in an itchy, burning rash lasting up to 12 hours.

Stinging nettle is invasive in the United States and can be found on forest edges and other natural areas. Stinging nettle is used in herbal medicine and in the kitchen. Consider using it to make pesto. 

a growing stinging nettle plant
Leila Haynes
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