22 Poisonous Plants in Ohio (and What to Do After Contact)

The poisonous plants that cause the most trouble in Ohio are poison ivy and wild parsnip, which injure skin, and poison hemlock, which has spread along roadsides and field edges across the state in recent years and can kill if eaten. Water hemlock, jimsonweed, pokeweed and several woodland wildflowers are also common. Even the state tree, the Ohio buckeye, has poisonous nuts. Poison oak, which appears on many Ohio lists, doesn’t grow in the state: what people call poison oak here is poison ivy.

If someone has eaten part of a plant, call Poison Control at 1-800-222-1222, which works anywhere in the US, around the clock. Call 911 for trouble breathing, seizures or unconsciousness. For pets, call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435.

• Plants That Burn or Blister Skin
• Wild Plants That Are Poisonous to Eat
• Garden and House Plants
• What to Do After Contact or Poisoning

Plant	Botanical name	Toxic part	Main risk
Poison Ivy	Toxicodendron radicans	All parts, including bare winter stems	Itchy, blistering rash (urushiol)
Poison Sumac	Toxicodendron vernix	All parts	Severe rash, stronger than poison ivy
Wild Parsnip	Pastinaca sativa	Sap	Burns and blisters in sunlight
Giant Hogweed	Heracleum mantegazzianum	Sap	Severe burns and blisters in sunlight; can damage eyes
Stinging Nettle	Urtica dioica	Stinging hairs on leaves and stems	Burning, itchy welts for a few hours
Flowering Spurge and Snow-on-the-Mountain	Euphorbia corollata, E. marginata	Milky sap	Skin rash; severe eye irritation; vomiting if eaten
Poison Hemlock	Conium maculatum	All parts	Paralysis; can be fatal
Spotted Water Hemlock	Cicuta maculata	All parts, especially the roots	Violent seizures; often fatal
Jimsonweed	Datura stramonium	All parts, especially the seeds	Hallucinations, racing heart, confusion
Pokeweed	Phytolacca americana	Roots, seeds, mature leaves and stems	Vomiting, diarrhea; the root is the most toxic
Horsenettle	Solanum carolinense	Berries, leaves; unripe fruit most toxic	Vomiting, stomach pain; a risk to children and livestock
White Snakeroot	Ageratina altissima	Leaves and stems	“Milk sickness” in people who drink milk from poisoned cows
Ohio Buckeye	Aesculus glabra	Nuts, leaves, bark and young shoots	Vomiting, diarrhea, weakness; poisons cattle
Mayapple	Podophyllum peltatum	Roots, leaves and unripe fruit	Severe vomiting and diarrhea
Jack-in-the-Pulpit	Arisaema triphyllum	All parts, especially the root	Intense burning and swelling of the mouth and throat
Bittersweet Nightshade	Solanum dulcamara	Berries, especially unripe, and leaves	Vomiting, diarrhea; a risk to children
White Baneberry (Doll’s Eyes)	Actaea pachypoda	All parts, especially the berries and roots	Burning mouth, stomach cramps, dizziness
Yews (Japanese and English Yew)	Taxus spp.	Needles, bark and seeds	Sudden heart failure; deadly to horses
Monkshood	Aconitum spp.	All parts, especially the roots	Numbness, vomiting, heart rhythm problems; can be fatal
Lily of the Valley	Convallaria majalis	All parts, including the red berries	Heart rhythm problems
Azaleas and Rhododendrons	Rhododendron spp.	Leaves, flowers, nectar	Drooling, vomiting, slow heart rate; dangerous for pets and livestock
Jerusalem Cherry	Solanum pseudocapsicum	Berries and leaves	Vomiting, diarrhea, drowsiness; a risk to children and pets

Plants That Burn or Blister Skin

These plants hurt you by touch, not by being eaten. Wear long sleeves, long pants and gloves when clearing brush or weeds, and wash your skin and tools afterwards.

Poison Ivy (Toxicodendron radicans)

Poison ivy grows in every Ohio county, in woods, hedgerows, fence lines, stream banks, parks and backyards. It can be a low groundcover, a shrub or a hairy vine climbing high into trees. Look for leaves of three leaflets, with the middle leaflet on a longer stalk. The leaflet edges can be smooth, toothed or lobed, and the leaves are often glossy and reddish in spring. All parts contain urushiol, an oil that causes an itchy, blistering rash in most people. It sticks to clothes, tools and pets’ fur, and stays active on bare winter vines. Never burn poison ivy: the smoke carries urushiol and can cause serious lung inflammation.

Poison Sumac (Toxicodendron vernix)

Poison sumac is a shrub or small tree, usually 5 to 20 feet tall, that grows only in wet ground such as bogs, fens and swamp edges, mostly in the northern half of Ohio. Each leaf has 7 to 13 smooth-edged leaflets on a red stalk, and in fall the plant carries loose, drooping clusters of whitish berries. Harmless sumacs, like staghorn and smooth sumac, have red berries in upright clusters and grow on dry ground. Poison sumac contains even more urushiol than poison ivy, and its rash is usually worse.

Wild Parsnip (Pastinaca sativa)

Wild parsnip is the escaped form of the garden parsnip. It is common along Ohio’s roadsides, bike trails, field edges and in unmown grass. It grows 2 to 5 feet tall, with a grooved stem, leaves made of toothed leaflets and flat clusters of small yellow flowers in June and July. Its sap makes skin extremely sensitive to sunlight (phytophotodermatitis). A day or two after contact, red, burn-like streaks and blisters appear where stems brushed bare skin. They can leave brown marks for months. Mowing or string-trimming it in shorts is the classic way to get burned.

Giant Hogweed (Heracleum mantegazzianum)

Giant hogweed is an invasive plant from the Caucasus that has been confirmed at a few sites in northeast Ohio. It is on Ohio’s noxious weed list. It is huge: 8 to 14 feet tall, with a purple-blotched, bristly stem 2 to 4 inches thick, deeply cut leaves up to 5 feet wide and white, umbrella-shaped flower heads up to 2 1/2 feet across. Its sap causes the same sunlight burn as wild parsnip, but much more severe, and sap in the eyes can cause lasting damage. Most “giant hogweed” reported in Ohio turns out to be the much smaller cow parsnip or wild parsnip. If you think you’ve found it, don’t touch it: report it to the Ohio Department of Agriculture.

Stinging Nettle (Urtica dioica)

Stinging nettle grows in moist, rich soil along streams, woodland edges and old farmyards. It is 3 to 7 feet tall, with square stems and opposite, heart-shaped to lance-shaped leaves that have coarsely toothed edges. Leaves and stems are covered in hollow hairs that inject histamine and other irritants when touched. The sting burns and itches for a few hours and is not dangerous. Young nettle leaves are edible once cooked or dried, because heat destroys the stinging hairs.

Flowering Spurge and Snow-on-the-Mountain (Euphorbia corollata, E. marginata)

Flowering spurge is a native wildflower of dry prairies, roadsides and old fields, 1 to 3 feet tall, with narrow leaves and airy clusters of small white “flowers” in summer. Its garden relative, snow-on-the-mountain, is a Great Plains annual grown for its white-edged leaves. Like all spurges, both ooze a milky latex when broken. The sap irritates skin and is very painful in the eyes, where it can cause temporary blindness. Eaten, it causes burning in the mouth, vomiting and diarrhea. Wear gloves and eye protection when cutting them back.

Wild Plants That Are Poisonous to Eat

These plants are only dangerous if swallowed. The two hemlocks are among the most poisonous plants in North America. Teach children never to eat any wild plant, berry or root without an adult who knows it.

Poison Hemlock (Conium maculatum)

Read our guide to Poison Hemlock

Poison hemlock is a European plant that has spread aggressively across Ohio since the 2010s, along highway medians, ditches, field edges and even into pastures and yards. It is 3 to 8 feet tall, with a smooth, hollow stem covered in purple spots, lacy, fern-like leaves that smell musty when crushed, and umbrella-shaped clusters of small white flowers from late May to July. It looks a lot like wild carrot (Queen Anne’s lace), but wild carrot has a hairy stem with no purple blotches. All parts contain coniine, which paralyzes the muscles, including those used for breathing. Eating a few leaves can kill an adult. The best time to control it is the first-year rosette, in fall or early spring. Wear gloves, because the sap can irritate skin.

Spotted Water Hemlock (Cicuta maculata)

Spotted water hemlock is a native plant of wet meadows, marshes, ditches and stream banks throughout Ohio, and it is often called the most toxic plant in North America. It is 3 to 7 feet tall, with smooth stems streaked or blotched with purple, leaves divided into narrow, toothed leaflets, and flat-topped white flower clusters in summer. Its roots are a bundle of thick tubers and contain cicutoxin, which causes seizures within 15 minutes to an hour of eating. A bite of root can kill an adult. Cattle often die after eating roots pulled up from wet ground.

Jimsonweed (Datura stramonium)

Jimsonweed is a coarse annual weed of farm fields, barnyards, vacant lots and gardens. It is 2 to 5 feet tall, with large, toothed leaves that smell unpleasant, white or pale purple trumpet-shaped flowers 3 to 4 inches long and spiny seed pods the size of a walnut. All parts contain tropane alkaloids (atropine and scopolamine). Poisoning causes dry mouth, dilated pupils, a racing heart, hallucinations and confusion that can last a day or more. Most serious cases are teenagers who eat the seeds or drink tea made from the plant, and deaths have occurred.

Pokeweed (Phytolacca americana)

Pokeweed is a big native perennial, 4 to 10 feet tall, that comes up in yards, fence rows, field edges and woodland clearings all over Ohio. It has thick magenta stems, large smooth leaves and drooping clusters of shiny, purple-black berries in late summer. All parts are poisonous. The large white taproot is the most toxic part and has been mistaken for horseradish or parsnip. Birds eat the berries safely, but children who eat them can get severe vomiting and diarrhea. Pull young plants before the taproot gets big, and wear gloves: the sap can irritate skin.

Horsenettle (Solanum carolinense)

Read our guide to Horsenettle

Horsenettle is a native perennial weed of pastures, gardens, fields and roadsides. It isn’t a nettle but a nightshade, 1 to 3 feet tall, with sharp yellowish spines on the stems and along the leaf veins. It has white to pale violet star-shaped flowers with a yellow center, followed by round, yellow berries that look like small tomatoes. All parts contain solanine. Eating the berries can cause vomiting, stomach pain and drowsiness. Its deep, creeping roots make it very hard to get rid of in a garden.

White Snakeroot (Ageratina altissima)

White snakeroot is a native woodland perennial, 1 to 4 feet tall, with toothed, oval leaves and flat clusters of small, fuzzy white flowers in late summer and fall. It contains tremetone, which poisons cattle, horses and goats that graze it. In the early 1800s, people who drank milk from those cows got “milk sickness”, which killed thousands of settlers across the Ohio Valley, including Abraham Lincoln’s mother. With today’s pooled and pasteurized milk it is a risk only to livestock and to people drinking raw milk from their own animals that graze woodland.

Ohio Buckeye (Aesculus glabra)

The Ohio buckeye has been Ohio’s state tree since 1953. It is a medium-sized native tree, 30 to 60 feet tall, with leaves of five leaflets spread like fingers and upright clusters of pale yellow-green flowers in spring. In fall its spiny husks split to show glossy brown nuts with a pale spot, said to look like a deer’s eye. The nuts look a lot like edible chestnuts, but they contain aesculin and saponins that cause vomiting, diarrhea and weakness. Young shoots and nuts also poison cattle and horses. Carrying a buckeye for luck is fine. Eating one is not.

Mayapple (Podophyllum peltatum)

Mayapple forms large colonies on the floor of Ohio’s deciduous woods. Each plant has one or two umbrella-like leaves, about a foot across, on a single stem. Plants with two leaves produce one waxy white flower in May, hanging underneath where it is easy to miss. The roots, leaves and green fruit contain podophyllotoxin, a strong purgative that causes violent vomiting and diarrhea. Only the fully ripe, soft yellow fruit is edible, and even then only the flesh, in small amounts, without the seeds.

Jack-in-the-Pulpit (Arisaema triphyllum)

Read our guide to Jack-in-the-Pulpit

Jack-in-the-pulpit is a native woodland wildflower, 1 to 2 feet tall, with one or two leaves of three leaflets each. In spring it has a hooded green or purple-striped flower (the “pulpit”), and in late summer a cluster of bright red berries. All parts are packed with needle-like calcium oxalate crystals. Biting into any part causes immediate, intense burning and swelling of the lips, tongue and throat. The pain usually stops people from swallowing much, but a swollen throat needs medical attention.

Bittersweet Nightshade (Solanum dulcamara)

Read our guide to Bittersweet Nightshade

Bittersweet nightshade is a sprawling European vine of hedgerows, thickets, stream banks and neglected garden corners. It has star-shaped purple flowers with a yellow cone in the middle, and clusters of oval berries that turn from green to orange to bright red. The berries contain solanine and related alkaloids. Children are drawn to them, and eating them causes vomiting, diarrhea and stomach pain. Older lists sometimes confuse it with climbing bittersweet (Celastrus scandens), a different native vine with orange-and-red fruit that is only mildly toxic.

White Baneberry (Doll’s Eyes) (Actaea pachypoda)

White baneberry is a native perennial of rich, shady woods, 1 to 2 feet tall, with large leaves divided into toothed leaflets. In spring it has a fluffy spike of small white flowers. In late summer these become the plant’s unmistakable fruit: white berries with a black dot, each on a thick red stalk, which is why it is called doll’s eyes. The berries are very bitter, so poisonings are rare, but eating them can cause burning in the mouth, stomach cramps, dizziness and, in large amounts, heart effects.

Garden and House Plants

These are grown on purpose in many Ohio homes and yards. They aren’t a reason to rip out your garden, but you should know which ones they are if you have small children, pets or livestock.

Yews (Japanese and English Yew) (Taxus spp.)

Yews are the dark green, needled shrubs used as foundation plantings and hedges around countless Ohio homes, mostly Japanese yew and its hybrids. The flat needles, bark and seeds contain taxine alkaloids, which can stop the heart. The red, cup-shaped “berries” are actually arils: the red flesh is not toxic, but the seed inside is. Horses, cattle and goats are killed every year by eating yew clippings, sometimes just a few mouthfuls, so never throw trimmings into a pasture.

Monkshood (Aconitum spp.)

Monkshood is a garden perennial, 2 to 4 feet tall, with deeply divided leaves and tall spikes of hooded blue or purple flowers in late summer and fall. It is one of the most poisonous garden plants. All parts contain aconitine, which causes tingling and numbness of the mouth, vomiting and dangerous heart rhythm problems within an hour of eating. The toxin can also be absorbed through broken skin, so wear gloves when dividing or cutting it. Ohio also has a rare native species, northern monkshood, which is federally listed as threatened.

Lily of the Valley (Convallaria majalis)

Lily of the valley is a European groundcover planted in shady Ohio gardens, and it often spreads into nearby woods. It has two or three broad leaves and a stem of small, fragrant, white bell-shaped flowers in May, followed by orange-red berries. All parts contain cardiac glycosides that can slow or disrupt the heart. Small children are at risk from the berries, and the plant is also dangerous for dogs and cats.

Azaleas and Rhododendrons (Rhododendron spp.)

Azaleas and rhododendrons are among the most popular flowering shrubs in Ohio yards, blooming in pink, red, purple, orange and white in spring. All parts contain grayanotoxins, which cause drooling, vomiting, weakness and a slow heart rate. People rarely eat enough to be harmed, but dogs, cats, goats and sheep that chew the leaves can be seriously poisoned. Honey made mostly from rhododendron nectar (“mad honey”) can poison people too.

Jerusalem Cherry (Solanum pseudocapsicum)

Jerusalem cherry is a small houseplant sold around the holidays for its glossy, round, orange-red berries, which look like cherry tomatoes. It is a nightshade, and the berries contain solanocapsine and other alkaloids. Eaten, they cause stomach pain, vomiting, diarrhea and drowsiness. Children and pets are the usual victims, so keep it out of reach or choose a different holiday plant.

What to Do After Contact or Poisoning

• Poison ivy or sumac: wash the skin with soap and cool water as soon as possible, ideally within 10 to 30 minutes, and wash clothes, gloves and tools separately. See a doctor if the rash covers a large area or reaches the face, eyes or genitals.
• Wild parsnip or hogweed sap: wash the skin right away with soap and water and keep it covered from sunlight for at least 48 hours. If sap gets in the eyes, rinse them with water and get medical help.
• Swallowed any plant on this list: call Poison Control at 1-800-222-1222. Keep a sample or photo of the plant for identification. Don’t wait for symptoms after eating poison hemlock, water hemlock or monkshood: call 911.
• Pets and livestock: call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435.
• Removing poison hemlock: wear gloves, long sleeves and eye protection, bag the plants rather than composting them, and never burn them.

Not on this list: poison oak (Toxicodendron diversilobum in the West and T. pubescens in the Southeast) doesn’t grow in Ohio. Spotted touch-me-not (jewelweed), sweet violet, great mullein and flax, which older lists include, are not meaningfully poisonous.

Related: Poisonous Plants Guide · Poisonous Plants in Pennsylvania · Poisonous Plants in Michigan