Poisonous plants are present in most cultivated gardens. Even very common plants that grow from ornamental bulbs have the capacity to poison if eaten. Poisonous plants include poison oak, daffodils, and giant hogweed.

Touching some plant saps, stems, or leaves may cause a skin rash. Parts of many plants may lead to severe gastrointestinal upset if eaten. Ingesting some plants may result in heart problems or nervous system issues.

This article will cover 10 poisonous plants, their identifiable features, and what to do if a person or pet has come into contact with them.

Poison ivy, oak, and sumac contain a substance called urushiol in the stems, roots, vines, flowers, and leaves.

Exposure to urushiol can result in the body developing a rash. The severity of the rash depends on the length of time a person has been in contact with it.

The Centers for Disease Control and Prevention (CDC) note that the plants grow in the following places:

  • Poison ivy: It grows in backyards or in woodland, and people can typically find it growing up fences, walls, or trees. The plant grows in all states of the United States, except Hawaii and Alaska.
  • Poison oak: It grows in backyards or in woodland and spreads when birds eat the berries. The poisonous plant is mostly located in western U.S., although there is a southeastern variant.
  • Poison sumac: It grows in wet or swamp areas and grows mainly in Eastern states.

How to identify

A person can use the following table to help identify poison ivy, oak, and sumac.

DescriptionSpringSummerFallWinter
SumacA red stem with 7–13 leaves per stem.Small green berries that are not perfectly round, with green leaves.Same as in spring.White berries
and red-orange leaves.
The leaves drop, but the bark is still poisonous.
IvyYoung plants have reddish leaves.

Mature plants have green leaves, but the new leaves are red.
Small clusters of green buds.Small greenish-white blooms with an orange centre.Pale green berries form and then turn white.
The leaves turn red, orange, or yellow.
The leaves drop, but the bark is still poisonous.
OakLobed leaves that look similar to oak leaves. Usually in threes.Leaves that are green and shiny and may have varying red parts.Clusters of small green flowers.Leaves that turn reddish.The leaves drop, but the cinnamon-colored bark is still poisonous.

Learn more about poison oak, poison ivy, and poison sumac rashes and how to treat them.

Giant hogweed has hollow stems that contain a noxious sap. This sap can cause the skin to blister when exposed to sunlight. The sap can also result in temporary or permanent blindness if it gets into the eyes.

Giant hogweed typically grows in North America and prefers cool environments with moisture, including:

  • along river banks
  • meadows
  • vacant lots
  • roadsides
  • rail tracks
  • ditches

How to identify

Giant hogweed grows up to 12–15 feet (ft) tall and 3-ft wide.

The flowers are white, flat-topped clusters at the top of the stem. The stems are thick, hairy, and green with purple blotches and have a ring of white hairs at the base of the stalk.

Daffodils contain lycorine which is a toxic chemical. Lycorine is most concentrated in the bulb.

Eating any part of a daffodil, including the bulb, will result in vomiting, nausea, pain in the abdomen, and diarrhea. Eating the bulb can also irritate the mouth.

The symptoms are not life threatening and will resolve in 3 hours.

How to identify

Long green leaves appear first, followed by a tall stem with a yellowish-green bud.

There are many different types of daffodil, but most have six petals surrounding a trumpet-like structure.

Poison hemlock is a member of the carrot family. All parts of the plant are toxic. It grows across most of North America.

Poison hemlock prefers to grow in shady areas with moist soil but infestations can occur along roadsides, pastures, marshes, and low-lying areas.

If ingested, the plant can slow down heart rate, damage the kidneys, and affect the nervous system, causing tremors and muscle damage.

Anyone who ingests poison hemlock should seek medical attention immediately.

How to identify

The plant can be difficult to identify as it looks similar to other edible plants.

Poison hemlock has lacy, fern-like leaves, green ribbed stems with purple blotches, and clusters of small white flowers that form an umbrella shape.

The fruit is egg-shaped, with wavy ribbing on the surface. The plant may also smell musty.

The seeds of a castor bean contain ricin which is released when the bean is chewed. Ricin is a toxin that prevents the body’s cells from producing proteins, which may be fatal.

The plant grows by roadsides, barnyards, stream beds, or dumping grounds.

How to identify

The University of Illinois College of Veterinary Medicine notes that castor bean can grow up to 15 ft. The large, star-shaped leaves have 5–11 toothed lobes and are glossy with bronze or red tints when immature.

The flowers are red, round, and feathery, in clusters at the top of the stem.

The manchineel tree grows on the shore of tropical climates and can grow in Florida.

All parts of the tree, including the fruit, are highly toxic. The tree sap can result in irritant contact dermatitis, leading to burning, itching, swelling, and blisters.

How to identify

Manchineel trees may have a red cross nearby to show the danger.

Manchineel has yellowish-brown variegated wood. The leaves are shiny with a smoothed edge and green.

Flowers are in spikes and are yellowing-green in color. The fruit looks like a small red or green apple.

All parts of the oleander plant are toxic. Oleandrin, an extract of the plant, may affect heart function and could prove lethal at the wrong dose.

Oleander is originally a Mediterranean plant but can adapt to many different types of soil. The plants have been planted on roadsides and in gardens.

Oleander is invasive at Death Valley National Park in California and Lake Mead National Park in Nevada. It is also common in Hawaii.

How to identify

Oleander is a round shrub with dense, dark green foliage.

The fragrant flowers are bright in color, with shades of pink, red, orange, yellow, or white.

Jimson weed grows in warmer climates in the U.S. on roadsides and in pastures.

Consumption of jimson weed can lead to:

Some people choose to consume the drug for its hallucinogenic properties. However, it can be fatal in high doses.

How to identify

Jinson weed grows up to 5-ft tall. The plant has a pale green stem with oval leaves that are green or have purple tinges with serrated edges.

The flowers are white or purple in a trumpet shape.

The reaction to poison shown will depend on the amount of exposure to the toxin.

If a person has touched a poisonous plant, they may develop:

People who have eaten or tasted a poisonous plant may show the following symptoms:

Pets

People should contact a vet as soon as possible if they suspect their pet has ingested a poisonous plant.

The signs that a pet has ingested a poisonous plant will depend on the type of plant. For example, the ingestion of a daffodil can cause:

  • salivation
  • vomiting
  • diarrhea
  • convulsions
  • low blood pressure
  • cardiac arrhythmias
  • tremors

If someone has come into contact with a toxic substance, take action immediately. First, reduce harm in one of the following ways:

  • For swallowed poison: If a person is experiencing burning or irritation and they are conscious, not having convulsions, and able to swallow, help them drink a small amount of water or milk.
  • For poison in the eye: Remove contact lenses and rinse the eye immediately under a running faucet for at least 15–20 minutes. Adults or older children may find it easier to rinse eyes in the shower.
  • For poison on clothing: Remove the contaminated clothing immediately and rinse the skin under running water.
  • For inhaled poison: Get to fresh air and stay away from the toxic fumes or gases.

    Next, contact Poison Control, or ask someone else to do this. There are two methods:
  • call Poison Control at 1-800-222-1222
  • use the POISONCONTROL tool

    Both options provide free, expert advice on what to do in a given situation and are available 24–7.

    Do not try to treat poisoning at home with ipecac syrup, charcoal, or other home remedies. These substances can be ineffective or even harmful.

It is important to note that the most lethal plants are typically uncommon, and it is rare that life threatening or severe consequences occur.

A person who has swallowed poisonous plants may not immediately realize what has happened. They should take pictures of the plant and seek medical help as soon as possible.

A person should do the following steps if they experience rashes or itching after coming into contact with a plant they should:

  • Rinse the skin.
  • Clean the nails with a nailbrush.
  • Apply soothing agents, such as calamine lotion, hydrocortisone cream, or wet compresses to aid itching.
  • Contact a medical professional if the rash affects the genitals or face.
  • Seek emergency treatment if a person experiences a severe allergic reaction or difficulty breathing.

Treatment typically involves treating the symptoms and providing support. In some cases, a person will require antidotes.

If a child swallows poison, a person should:

  • avoid making them vomit
  • take the poison plants away from the child
  • call 911 or an emergency helpline for further instructions

If there is any substance still in the mouth, get the child to spit it out or use the fingers to remove it. People should then keep it as evidence of what the child has swallowed. It is also beneficial to take a picture of the plant.

Poison.org suggests calling 911 or an emergency line immediately for advice. People should not attempt to make a person vomit. They should take a picture of the plant, including leaves, fruit, and roots if visible.

If the mouth or throat is burning, a person can drink a small amount of milk or water, providing they are conscious, are not having convulsions, and can swallow the drink.

There are many poisonous plants that people encounter in their day-to-day lives.

Some plants can cause reactions on the skin if a person touches them. If a person swallows a poisonous plant, they may experience gastrointestinal upset. In rare cases, ingesting poisonous plants can be fatal.

If a person ingests a poisonous plant, they should contact a medical professional for advice.

It can be beneficial to know the poisonous plants that a person may encounter in an area and how to identify them.