17 Common Weeds That Are Dangerous for Pets

Spending time in nature is healthy and beneficial for both you and your pet. Unfortunately, that inviting field of wildflowers your dog or cat may love to explore can harbor potentially dangerous weeds.

Keep an eye out for hazardous weeds whenever your pet travels through a new area. Also, check your pet once they get home to remove any thorns, spines, or burs lodged in their fur or skin. And lastly, watch for any signs they have eaten anything harmful, such as vomiting or diarrhea.

If you have any concerns that your pet has come in contact with dangerous wild plants, contact your veterinarian immediately.

These are some common weeds to avoid so you and your pet can safely enjoy the outdoors.

Ammi majus

1. Bishops Weed

Also known as bullwort, greater ammi, false Queen Anne’s lace, or laceflower. Bishop’s weed grows up to 3 feet (91 centimeters) with umbrella-like, white blossoms. It’s dangerous for most animals, including livestock.

Dangers: Photosensitization when ingested, which can lead to serious sunburns, swelling and blisters. Humans can also become photosensitive when they touch bishop’s weed before exposure to sunlight.

Range: Originated in the Nile River Valley, now spread throughout Europe, Asia, and the Americas.

Scientific Name: Ammi majus

Bur Chervil

2. Bur Chervil

This aggressive plant can outcompete most other species and often forms large monocultures. It has small, white flowers and fern-like leaves. The tiny, hard fruits are covered in hooked spines.

Dangers: The spiny fruit pods can become stuck in animals’ fur and cause pain and possible infection.The leaves also contain toxins that can irritate human skin.

Range: Native to Europe, spread to Asia and North America.

Scientific Name: Anthriscus caucalis

Burdock

3. Burdock

Burdock roots and leaves are eaten by humans for food and medicinal purposes. It’s the mature seed pods, or burs, that are a problem for pets.

Dangers: The burs can stick to animals’ fur, which can be painful, but also a nuisance to remove as they often attach in large numbers.

Range: Native to Europe, now common throughout the world.

Scientific Name: Arctium species

Cactus

4. Cacti

There are over 1750 known species of cacti worldwide. You can recognize these succulent plants by their sharp spines, which are actually modified leaves. Taller species of cacti are obvious in a landscape, but smaller cacti can easily hide amongst grasses or other groundcovers.

Dangers: The spines can pierce your pet’s skin. Certain cactus species have small, delicate spines that can break and leave segments underneath the skin. This increases the risk of infection.

Range: Dry regions throughout the world.

Scientific Name: Various

California burclover
Photo credit: Forest & Kim Starr, via Wikimedia Commons

5. California Burclover

Also known as toothed bur clover, toothed medic, or burr medic. This plant is a low-growing groundcover with small, yellow flowers. The mature burs are covered in spines that can stick to fur or skin.

Dangers: The burs can readily work their way into pet hair and ears. They can also attach to human skin, such as the bottom of your feet.

Range: Native to the Mediterranean, now spread globally.

Scientific Name: Medicago polymorpha

Solanum dulcamara

6. Climbing Nightshade

Also known as bittersweet nightshade, violet bloom, poisonflower, Devil’s apple, or blue bindweed. This plant is a semi-woody perennial vine that can reach up to 4 meters (13 feet) long. The fruit is an attractive red berry. All plant parts, especially the berries, are poisonous to many animals, including humans.

Dangers: Common effects from ingestion include diarrhea and vomiting. Less common effects are drowsiness, convulsions, low blood pressure, and low heart rate.

Range: Native to Europe and Asia, now naturalized internationally.

Scientific Name: Solanum dulcamara

Cicuta_virosa
Photo credit: By Kristian Peters, via Wikimedia Commons

7. Cowbane

Also known as water hemlock or poison parsnip. Cowbane typically grows in wet, marshy places and can be easily confused with other similar, non-toxic flowers. All parts of the plant contain cicutoxin, which is toxic to pets, livestock, and humans.

Dangers: Ingestion can lead to diarrhea, vomiting, bloating, seizures, and even death.

Range: Native to temperate regions of the Northern Hemisphere, mainly North America and Europe.

Scientific Name: Cicuta species

450px-Torilis_arvensis_sl14
Photo credit: By Stefan.lefnaer, via Wikimedia Commons

8. Hedge Parsley

Hedge parsley has a white, umbel-like flower similar to Queen Anne’s lace. Often found in meadows, along roadsides, or other disturbed areas. The abundant seeds have a dense covering of bristles.

Dangers: The seeds can stick to fur or clothing, causing pain, discomfort and difficulty removing them in large numbers.

Range: Native to Eurasia and North Africa, spread to other continents.

Scientific Name: Torilis arvensis

450px-Conyza_canadensis_5
Photo credit: By Dalgial, via Wikimedia Commons

9. Horseweed

Also known as butterweed or fleabane. It is a common weed of fields and meadows, with around 50 different species worldwide. Horseweed is an aggressive competitor for water that grows rapidly. Livestock do not graze on horseweed and it can become problematic in agricultural areas.

Dangers:Leaves and flowers contain a terpene that can cause skin and mucosal irritation in humans and other animals on contact. Ingestion can also lead to vomiting and diarrhea.

Range: Native to many regions throughout the world.

Scientific Name: Conyza species

Foxtail barley

10. Grass Awns (Foxtails)

The mature seed heads of wild grasses, also called foxtails, can look very picturesque blowing in the wind on a mid-summer’s day. But the individual seeds, or grass awns, often have barbs that are meant to dig into soil, which will also dig into an animal’s skin. MeanSeeds has a good list of bad grasses to watch out for, as well as other helpful information about grass awns.

Dangers: Grass awns can lodge in your pet’s eyes, ears, nose, mouth, tail, throat, and in between toes. These can become infected and may ooze pus, blood, or fluid. Grass awns can also migrate within the body over time, and potentially reach your pet’s heart, lungs, or other internal organs.

Range: Many different native grasses throughout the world.

Scientific Name: Various species

Ragwort

11. Groundsel (Ragwort)

There are many different species of groundsel, and all of them can be toxic to pets, livestock, and humans. All plant parts contain pyrrolizidine alkaloids, which are harmful to the liver when consumed in large enough quantities.

Dangers: Weight loss, weakness, sleepiness, incoordination, yellowish discoloration of mucous membranes, and potential liver failure.

Range: Worldwide.

Scientific Name: Senecio species

800px-DATURA_STRAMONIUM_-_GUIXERS_-_IB-615
Photo credit: By Isidre blanc, via Wikimedia Commons

12. Jimsonweed

Also known as thorn apples or Devil’s trumpet. All plant parts contain dangerous levels of certain tropane alkaloids, which interfere with chemical messengers in the brain and nerves of most animals, including humans.

Dangers: Ingestion can cause extreme thirst, vision problems, nausea, vomiting, fast heart rate, hallucinations, seizures, loss of consciousness, breathing problems, and possible death.

Range: Native to North America, now spread throughout most warm regions of the globe.

Scientific Name: Datura stramonium

Related: 23 Common Plants Poisonous to Pets

Milkweed

13. Milkweed

There are many different species of milkweed. Some species contain cardiotoxins and others contain neurotoxins. All parts of the plants are toxic, both when fresh or dried out at the end of the season.

Dangers: Ingestion can lead to abdominal pain, vomiting, diarrhea, staggered gait, difficulty breathing, rapid or weak pulse, or other cardiac abnormalities. Other possible effects include liver or kidney failure, respiratory paralysis, coma or death.

Range: Native to many regions of North America.

Scientific Name: Asclepias species

Sweet Pea

14. Perennial Sweet Pea

Perennial sweet peas have a sweet-pea-shaped, pink blossom, but no smell. The most toxic parts of the plants are the mature seed pods. These typically only cause gastrointestinal upset when eaten infrequently by pets. Although, long-term consumption, primarily by livestock, can lead to more serious complications.

Dangers:Ingestion can cause weakness, head pressing, tremors, seizures, urinary incontinence, and possible death.

Range: Native to Europe, spread to North America and Australia.

Scientific Name: Lathyrus latifolius

800px-Tribulus_terrestris_Russia_(habitus)
Photo credit: By Le.Loup.Gris, via Wikimedia Commons

15. Puncturevine

Also known as caltrop, cat’s head, Devil’s thorn, and tackweed. It has adapted to survive in desert climates and poor soil. The yellow flowers are soon followed by a fruit made up of five hard nutlets, or burs. Each nutlet has two to four sharp spines that can stab into skin and flesh. The spines are sharp enough to even puncture bicycle and lawnmower tires.

Dangers: Cuts and skin punctures from stepping on nutlets.

Range: Warm and tropical regions worldwide.

Scientific Name: Tribulus terrestris

Wild Chives

16. Wild Onions

Sulfur compounds in all types of onions are dangerous for many animals, such as dogs, cats, and horses. These compounds harm the cell membranes of red blood cells. Plants in this family to watch out for include chives, leeks, garden and wild onions, and garlic.

Dangers: Ingestion can cause the breakdown of red blood cells, leading to anemia, blood in urine, high heart rate, and panting.

Range: Worldwide.

Scientific Name: Allium species

Yarrow grows on a meadow in the natural environment. Selective focus

17. Yarrow

Yarrow is found from sea level to 3,500 meters (11,500 feet) elevation. The wild plant has white flowers, and many different colored varieties have been bred for ornamental gardens. Yarrow can be toxic, although pets rarely eat enough to cause serious harm because the plant is fairly pungent and unappetizing.

Dangers: Increased urination, vomiting, diarrhea, anorexia, and skin irritation when touched. May also cause miscarriage in pregnant animals. Symptoms may be worse in animals who already have existing allergies to other plants and pollen.

Range: Native to Asia, Europe, and North America, introduced to Australia and New Zealand.

Scientific Name: Achillea millefolium

Related:
Why You’re a Mosquito Magnet, According to Science
10 Spring Plants That Are Dangerous for Pets
12 Dangerous Bugs You Don’t Want to Mess With

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340 comments

Margie F
Margie F1 months ago

I have only onion weed with regard to the above. I do use Basil in the food they eat, which is high in vitamin K.

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Cindy M. D
Cindy M. Dutka1 months ago

Shared with all my family and friends. We must be aware of how to keep our beloved pets safe. TYFS!!

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W. C
W. C1 months ago

Thanks.

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William C
William C1 months ago

Thank you.

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Olga T
Olga Troyan1 months ago

What an interesting article, thank you.

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Elizabeth W
Elizabeth W1 months ago

Quite terrifying what some of those plants can do - who knew?

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Richard A
Richard A1 months ago

Thank you for this helpful article.

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Mike H
Mike H1 months ago

Thank you

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Andrea B
Andrea B1 months ago

Thanks

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bob P
bob Petermann1 months ago

Thanks for the information.

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