25 Poisonous Plants in Pennsylvania (and What to Do After Contact)

The poisonous plants you are most likely to meet in Pennsylvania are poison ivy, which grows in every county, and wild parsnip and giant hogweed, whose sap burns skin in sunlight. The most dangerous to eat are poison hemlock and water hemlock, both of which can kill. Pokeweed, jimsonweed and several woodland wildflowers are also common. Even the state flower, mountain laurel, is poisonous. Poison oak, which appears on many Pennsylvania 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 Landscape 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
Giant Hogweed	Heracleum mantegazzianum	Sap	Severe burns and blisters in sunlight; can damage eyes
Wild Parsnip	Pastinaca sativa	Sap	Burns and blisters in sunlight
Stinging Nettle	Urtica dioica	Stinging hairs on leaves and stems	Burning, itchy welts for a few hours
Poison Hemlock	Conium maculatum	All parts	Paralysis; can be fatal
Spotted Water Hemlock	Cicuta maculata	All parts, especially the roots	Violent seizures; often fatal
Pokeweed	Phytolacca americana	Roots, seeds, mature leaves and stems	Vomiting, diarrhea; the root is the most toxic
Jimsonweed	Datura stramonium	All parts, especially the seeds	Hallucinations, racing heart, confusion
White Snakeroot	Ageratina altissima	Leaves and stems	“Milk sickness” in people who drink milk from poisoned cows
White Baneberry (Doll’s Eyes)	Actaea pachypoda	All parts, especially the berries and roots	Burning mouth, stomach cramps, dizziness
Mayapple	Podophyllum peltatum	Roots, leaves and unripe fruit	Severe vomiting and diarrhea
Bloodroot	Sanguinaria canadensis	Root and orange-red sap	Vomiting, low blood pressure; the sap burns skin
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
Virginia Creeper	Parthenocissus quinquefolia	Berries; sap in sensitive people	Stomach upset and mouth irritation if eaten
Marsh Marigold	Caltha palustris	All parts, raw	Burning mouth, vomiting; sap blisters skin
Fly Poison	Amianthium muscitoxicum	All parts, especially the bulb	Vomiting, weakness, breathing problems; kills livestock
Mountain Laurel	Kalmia latifolia	Leaves, flowers, twigs; honey made from it	Vomiting, low heart rate; kills goats and sheep
Yews (Japanese, English and Canada 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
Autumn Crocus (Meadow Saffron)	Colchicum autumnale	All parts, especially the corm	Severe vomiting and diarrhea, organ failure; can be fatal
Boxwood	Buxus sempervirens	Leaves and twigs	Vomiting and diarrhea; mainly a risk to pets and horses
Irises (Including Northern Blue Flag)	Iris spp.	Rhizomes and bulbs; less so leaves	Vomiting, diarrhea; sap irritates skin

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 throughout Pennsylvania, in woods, hedgerows, fence lines, stream banks and yards. 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 it stays active on bare winter vines. Never burn poison ivy: the smoke can carry urushiol into your lungs.

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, swamps and wet woods. It is scattered across Pennsylvania but much less common than poison ivy. 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.

Giant Hogweed (Heracleum mantegazzianum)

Giant hogweed is an invasive plant from the Caucasus that has been found at scattered sites across Pennsylvania, especially in the northwest and southeast, and is on the state’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 makes skin extremely sensitive to sunlight (phytophotodermatitis). Burns and blisters appear 1 to 2 days after contact and can leave scars for years. Sap in the eyes can cause lasting damage. Don’t touch it or cut it yourself: report it to the Pennsylvania Department of Agriculture, which runs an eradication program.

Wild Parsnip (Pastinaca sativa)

Wild parsnip is the escaped form of the garden parsnip. It is now common along roadsides, trails and field edges across Pennsylvania and far more widespread than giant hogweed. 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 causes the same sunlight burn as giant hogweed, on a smaller scale. The typical injury is a streaky row of blisters where stems brushed bare legs or arms, often after mowing or string-trimming in shorts.

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.

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 along roadsides, ditches, stream banks and field edges throughout Pennsylvania. 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. Wear gloves if you pull it, because the sap can also irritate skin.

Spotted Water Hemlock (Cicuta maculata)

Spotted water hemlock is a native plant of wet meadows, marshes, ditches and stream banks, 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. Many poisonings happen when people mistake the root for wild parsnip or wild carrot.

Pokeweed (Phytolacca americana)

Pokeweed is a big native perennial, 4 to 10 feet tall, that pops up in yards, fence rows, field edges and woodland clearings all over Pennsylvania. It has thick magenta stems, large smooth leaves and drooping clusters of shiny, purple-black berries in late summer that stain everything purple. 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. Some people cook the young spring shoots as “poke sallet”, boiling them in several changes of water, but that is not a safe experiment for beginners.

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.

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 in the Ohio Valley, including Abraham Lincoln’s mother, Nancy Hanks Lincoln, in 1818. With today’s pooled and pasteurized milk, it is a risk only for livestock and for people drinking raw milk from their own animals that graze woodland.

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.

Mayapple (Podophyllum peltatum)

Mayapple forms large colonies on the floor of Pennsylvania’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.

Bloodroot (Sanguinaria canadensis)

Bloodroot is one of the first wildflowers to bloom in Pennsylvania woods, in March and April. Its single white flower with 8 to 12 petals opens while a single, lobed leaf is still wrapped around the stem. Break the root or stem and it bleeds orange-red sap, which contains sanguinarine. Eaten, it causes vomiting, dizziness and low blood pressure. Bloodroot is the main ingredient of “black salve”, an unapproved skin cancer remedy that destroys healthy skin and leaves deep scars. The FDA warns against using it.

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 that grows in 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. It is a relative of the tomato and potato, and is not the same plant as the bittersweet (Celastrus) used in fall wreaths.

Virginia Creeper (Parthenocissus quinquefolia)

Virginia creeper is a common native vine that climbs trees, walls and fences with sticky tendril pads, and turns brilliant red in fall. It is often confused with poison ivy, but it has five leaflets, not three. Its small blue-black berries contain oxalate crystals and can cause mouth irritation, stomach pain and vomiting if eaten, so they are a concern for small children. The sap can cause a mild rash in some people, but nothing like poison ivy.

Marsh Marigold (Caltha palustris)

Marsh marigold is a native plant of wet woods, swamps, seeps and stream banks. In April and May it covers wet ground with glossy, kidney-shaped leaves and bright yellow, buttercup-like flowers, 1 to 1 1/2 inches wide. Like buttercups, it contains protoanemonin, which blisters the mouth and skin and causes vomiting and diarrhea if eaten raw. Old recipes for cooked marsh marigold greens exist, but the plant is easily mixed up with other wetland plants and isn’t worth the risk.

Fly Poison (Amianthium muscitoxicum)

Fly poison is a native wildflower of open woods and forest edges, found mostly in the southern half of Pennsylvania. It has grass-like leaves from a bulb and, in early summer, a dense spike of small white flowers on a stalk 1 to 3 feet tall. The flowers turn greenish as they age. Its name comes from the old practice of mixing the crushed bulb with sugar to kill flies. All parts contain toxic alkaloids. It is mostly a risk to grazing cattle and sheep, but it is dangerous for people too.

Garden and Landscape Plants

These are grown on purpose in many Pennsylvania 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.

Mountain Laurel (Kalmia latifolia)

Mountain laurel has been Pennsylvania’s state flower since 1933. It is a native evergreen shrub, 5 to 15 feet tall, that forms dense thickets in the state’s forests and is also planted in shady gardens. It flowers in late May and June, with clusters of cup-shaped pink or white flowers. The leaves are leathery, glossy and oval. All parts contain grayanotoxins, which cause drooling, vomiting, a slow heart rate and low blood pressure. People are rarely poisoned, but goats, sheep and cattle that browse the evergreen leaves in winter often are.

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

Yews are the dark green, needled shrubs used as foundation plantings and hedges around countless Pennsylvania homes. Most are Japanese yew or its hybrids. Canada yew is a low native species of cool, shady woods. 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.

Lily of the Valley (Convallaria majalis)

Lily of the valley is a European groundcover planted in shady gardens throughout Pennsylvania, 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.

Autumn Crocus (Meadow Saffron) (Colchicum autumnale)

Autumn crocus is a garden bulb, not a wild plant. Its pink or lilac crocus-like flowers appear in September and October, with no leaves. The broad leaves come up in spring and die back by early summer. All parts contain colchicine. Poisonings happen when the spring leaves are mistaken for wild leeks (ramps), which are popular with Pennsylvania foragers and come up at the same time. Symptoms start hours after eating, and severe cases can be fatal.

Boxwood (Buxus sempervirens)

Boxwood is the small-leaved evergreen shrub used for low hedges and edging in formal gardens. It has small, glossy, oval leaves and a distinctive smell that some people find unpleasant. The leaves contain steroidal alkaloids that cause vomiting and diarrhea. They taste very bitter, so people rarely eat enough to be harmed, but dogs that chew the branches and horses that eat clippings can be poisoned. Sap can irritate sensitive skin.

Irises (Including Northern Blue Flag) (Iris spp.)

Pennsylvania gardens grow bearded, Siberian and Japanese irises, and the native northern blue flag (Iris versicolor) grows in marshes and wet meadows. All irises contain irritating compounds, mostly in their thick underground rhizomes or bulbs. If eaten, they cause burning in the mouth, vomiting and diarrhea, and the sap can cause a rash. Dogs that dig up and chew rhizomes are the most common victims.

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.
• Hogweed or wild parsnip 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, monkshood or autumn crocus: call 911.
• Pets and livestock: call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435.

Not on this list: poison oak (Toxicodendron diversilobum in the West and T. pubescens in the Southeast) doesn’t grow in Pennsylvania. Canada thistle, flax and fiddleneck, which older lists include, are either not meaningfully poisonous or don’t grow here.

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