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14 Plants That Look Like Poison Hemlock 

The world is full of beautiful plants to admire and appreciate. Some wild plants grow blossoms that are great additions to the dining room table. Others attract wild pollinators. Even more plants improve soil quality. This article discusses several different plants that some say look like poison hemlock. We’ll examine the plant’s blooms, leaves, stems, and other characteristics. 

Wild hemlock (Conium maculatum) is a well-known poisonous plant that can cause illness and even death. If you’re hiking in a new place or investigating the plants in your backyard, keep an eye out for poison hemlock. It’s easy enough to avoid when hiking. If it’s in your backyard, however, we recommend removing it. 

Poison Hemlock History

All the parts of this plant are dangerous. In fact, the stems of poison hemlock are still lethal even 3 years after they are dried! It’s no coincidence that hemlock was used in ancient times as poison. The ancient Greeks put criminals to death by making them drink a liquid brewed with poison hemlock juice.

Poison hemlock is native to Europe, Asia, and Africa. It was introduced to North America in the 19th century, despite its toxic effects on most mammals. It established wild populations after the seeds escaped from flower gardens. 

Basic Poison Hemlock Characteristics

Before we dive into a list of all the plants we could mistake for poison hemlock, let’s take a look at poison hemlock’s traits. Knowing what to avoid will help you spot poison hemlock, even if all of the points we discuss aren’t present. 

This weedy plant grows in recently disturbed areas. Look for it alongside roads, pasture edges, and drainage ditches. It’s especially problematic if it shows up where livestock graze; it can kill cattle. 

Poison hemlock plants grow on a two year cycle. They have rich green leaves that look like carrot tops for the first year, and grow about 2 feet tall.

The second year sees the plant grow a central stalk up to 10 feet tall. Upon this blotchy stalk, the plant develops flower buds that eventually bloom into small white blossom clusters. 

14 Plants that Look Like Poison Hemlock 

When making this list of poison hemlock lookalikes, we separated the similar plants into poisonous and nonpoisonous categories. This may help you further narrow down what plants to avoid. 

Poisonous Lookalikes 

These plants are not poison hemlock, but they are poisonous. They should be avoided along with poison hemlock.

1. Fool’s Parsley 

Fool’s parsley 
Fool’s parsley  | image by Gertjan van Noord via Flickr | CC BY-ND 2.0

Scientific name: Aethusa cynapium

Fool’s parsley is a common invasive weed from Europe that was introduced to North America. It shares white flowers and parsley-like leaves with poison hemlock. Tell it apart from poison hemlock based on its height (almost 2 ½ feet tall). This plant is also poisonous in its own right. 

Livestock that eat fool’s parsley fresh from the field will experience digestive upset and may even die, but the plant does not pose a health risk when dried. It can be harvested and dried in hay and fed without problem. 

2. Giant Hogweed

Giant hogweed by Bill Kasman via Flickr

Scientific name: Heracleum mantegazzianum

Giant hogweed takes the prize for the tallest plant on this list. It grows over twice as tall as a poison hemlock. The average giant hogweed plant reaches between 15 and 20 feet tall! 

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Like poison hemlock, giant hogweed is invasive. They share a blotchy purple stem as well. Giant hogweed flowers are yellow, not white.

Their leaves don’t have as much detail or ‘lacy’ indentations made. Exposure to giant hogweed sap causes sun sensitivity and large blisters. 

3. Cowbane

Cowbane
Cowbane | image by Gertjan van Noord via Flickr | CC BY-ND 2.0

Scientific name: Cicuta virosa 

Cowbane is also known as northern water hemlock. This plant is a relative of poison hemlock and is just as lethal. Its flowers are very similar to those of the poison hemlock; small, white, and arranged in clusters.

The stems are similarly blotched with purple. Only the leaves are slightly different. Instead of a complex ‘lacey’ pattern, they are oval-shaped with deep serrated edges.

Look for cowbane along the edges of wetlands and open meadows with abundant standing water. Just one bite from the root of the plant can kill a sheep or horse. 

4. Western Water Hemlock

Western water hemlock
Western water hemlock | image by James St. John via Flickr | CC BY 2.0

Scientific name: Cicuta douglasii

Western water hemlock is a water-loving poisonous plant that grows throughout North America. Unlike most of the plants on this list, it was not introduced to the western hemisphere.

It is instead native to North America. Populations are highest in the Western United States, especially the Rocky Mountains and the Pacific Northwest. British Columbia has a substantial population. 

This plant resembles poison hemlock in terms of flowers and stem color. Both have small white flowers that bloom in umbrella-like forms called ‘umbels.’ They share purple-streaked stems as well.

Western water hemlock doesn’t grow as tall, though – its maximum height is 6 ½ feet. It’s a major safety risk for livestock, as it can kill in as little as a quarter hour. 

5. Wild Parsnip

Wild parsnip
Wild parsnip | image by Andreas Rockstein via Flickr | CC BY-SA 2.0

Scientific name: Pastinaca sativa 

Wild parsnip can have deleterious effects upon contact with the skin. This occurs in both humans and livestock.

If a person or animal is exposed to the sap of the wild parsnip and then is exposed to sunlight, their skin will blister and peel. Permanent scarring may occur, as well as months of skin discoloration.

It has small yellow flowers that bloom on top of a flat umbel. Young plants’ leaves are rounded with sharp lobes. As the plant grows, the lobes become serrated and the leaf becomes pointy.

Stems will never get blotchy or purple; they are always bright green. These plants grow up to 5 feet in height. 

6. Cow Parsnip

Cow parsnip
Cow parsnip | image by Dr. Alexey Yakovlev via Flickr | CC BY-SA 2.0

Scientific name: Heracleum lanatum 

Despite its name, cow parsnip is not a good food for cows. It’s toxic to livestock and should be treated as a noxious weed.

Cow parsnips’ flowers are large and easy to tell apart from poison hemlocks’. The blooms crowd together on a flat umbel similar to the heads of cauliflower. 

The maximum size for these perennial plants is 8 feet. Most average between 4 to 6 feet tall. They are host to the anise swallowtail butterfly, which causes friction between conservationists and ranchers. 

Non-poisonous Lookalikes

These plants don’t pose a poisoning risk to humans and animals. They may be host to pest species like ticks, but they do not contain poisonous compounds unless otherwise stated in the description (#11).

7. Queen Anne’s Lace 

Queen anne’s lace
Queen anne’s lace | image by Andreas Rockstein via Flickr | CC BY-SA 2.0

Scientific name: Daucus carota

Queen Anne’s lace is so named after the lacy appearance of the white flowers on this wild biennial. It’s also known as the ‘wild carrot,’ but it’s rarely cultivated for food. It was introduced to the United States as a flower garden plant, but like many species, quickly established wild populations. 

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This plant shares a few similarities with poison hemlock: both have white flowers, live for two years, and lacy leaves. However, Queen Anne’s lace grows only 3 feet tall, flowers long into the fall, and has a hairy, unblotched stem.  

8. Common Yarrow

Common yarrow
Common yarrow | image by Andreas Rockstein via Flickr | CC BY-SA 2.0

Scientific name: Achillea millefolium 

Common yarrow looks similar to poison hemlock during the first year of the poison hemlock’s life. The two plants have similar leaves: both are detailed and somewhat fern-like. Lucky for the amateur naturalist, the similarities end there. 

This plant usually has one primary stem between 1 and 3 feet tall. Small fernlike leaves grow at regular intervals off of the stem.

At the top, there are many tiny white flowers balanced on flattened disks. Look for them throughout the United States; they are adaptable, common, and used to feed livestock. 

9. Osha

Osha
Osha | image by JOE BLOWE via Flickr | CC BY-SA 2.0

Scientific name: Ligusticum porteri

Osha is a common herb utilized in traditional Native American medicine. It’s shorter than poison hemlock – it maxes out at 3 feet tall. The tiny flowers are on long stems, not umbrella-like umbels.

Tell it apart from poison hemlock and water hemlock by looking at the roots: the skin on the outside of the root is dark brown and wrinkly. Poisonous hemlocks’ roots are white. 

Osha is a species native to North America. It grows in the Rocky Mountain region, especially along the edges of forests and in ravines and valleys. Unless you live a mountainous part of the western United States, you are unlikely to see this rare relative of the poison hemlock plant. 

10. Wild Chervil 

Wild chervil
Wild chervil | image by Andreas Rockstein via Flickr | CC BY-SA 2.0

Scientific name: Anthriscus sylvestris 

Wild chervil goes by many names, including cow parsley, keck, and even Queen Anne’s lace. We include the scientific names in this article to help you identify these plants more easily.

Wild chervil does share a few traits with poison hemlock: white flowers, deep green leaves, and a love of high disturbance areas. However, there are some easy ways to tell it apart. 

First, wild chervil’s stems are slender and unblemished. It is more sparsely foliated – there are fewer stems and leaves – than poison hemlock. Its flowers are more sparse, but bigger. 

Note that all of the wild chervil plant is edible. Make sure you’re confident in your identification before you snack!

11. Elderflower

Elderflower
Elderflower | image by Dr. Hans-Günter Wagner via Flickr | CC BY-SA 2.0

Scientific name: Sambucus spp. 

Elderflower has been in vogue in the last several years, and for good reason. A tincture made from elderberries is effective against colds and viruses. This has made growing elderflowers more popular than ever, especially since a syrup made from the dark purple berries is easy to make.

The elderflower plant’s leaves are not as fernlike as poison hemlock’s leaves. They are oval in shape and yellow-green. Both plants’ flowers are white, but the elderflower’s flowers are not in the same umbel form as the poison hemlocks’. 

If you choose to grow your own elderflower, remember that all berries must be cooked before consumption. They are poisonous raw! 

12. Wild Fennel

Fennel
Fennel | image by Forest and Kim Starr via Flickr | CC BY 2.0

Scientific name: Foeniculum vulgare

It may be a surprise to discover that domestic fennel and wild fennel are one and the same; they’re exactly alike except for what side of the garden fence they’re on. Wild fennel is an introduced species from Europe that was planted in kitchen gardens to add flavor and depth to food dishes. After seeds escaped into the wild, they established thriving ‘feral’ populations. 

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Wild fennel can grow to massive dimensions – sometimes over 5 feet wide by 8 feet tall! It’s considered invasive in most of the places it grows, so it’s alright to take some for yourself.

Tell it apart from hemlock according to leaf color and shape. Fennel has tiny, bright green, needle-like leaves. It also smells pleasant.

13. Pignut 

Pignut plant
Pignut plant | image by janet graham via Flickr | CC BY 2.0

Scientific name: Conopodium majus 

Pignut is a non-woody herbaceous plant that grows throughout the open areas and woodlands of Europe. Populations have yet to become established in North America, but it looks similar enough to poison hemlock that we recommend being able to identify it even if you’re in the Western Hemisphere. 

Pignut grows up to 16 inches tall, has lacy leaves, and small white flowers on flattened umbels. Compared to poison hemlock, the leaves look more similar to bamboo. Colonies of pignut are common throughout the English and Scottish countryside. 

14. Purple Angelica 

Purple-stem angelica
Purple-stem angelica | image by Joshua Mayer via Flickr | CC BY-SA 2.0

Scientific name: Angelica atropurpurea 

Purple angelica is a sweet-smelling wild plant that looks similar to poison hemlock but doesn’t pose a health or safety risk. Its white flowers have a greenish tint that will help you tell the two plants apart. It gets its name from its purple stem. 

The plant’s leaves are the best way to differentiate it from poison hemlock. They are lighter green in color, have less ‘lacy’ detail, and are oval shaped. Poison hemlock leaves look much more like parsley or carrot greens.