10 Plants That Look Like Poison Hemlock and How to Identify Each

close up wild white flowers of hemlock plant
© iStock.com/gabrielabertolini

Written by Jennifer Hollohan

Updated: January 1, 2024

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If you spend time outside, you have likely heard about poison hemlock (Conium maculatum). This highly toxic plant poses a significant danger, so understanding how to identify it is vital. However, some other plants look similar to poison hemlock at first glance. Knowing what to look for will help keep you and your pets safe. It is a biennial plant that grows relatively low to the ground the first year but shoots up to 10 feet high the second year. When young, its fern-like foliage resembles carrots, which makes sense as it belongs to the Apiaceae (carrot) family. The stalk is hollow and smooth, with no hairs. It also has purple or red dots and streaks. Its bright green leaves are lacy, divided, and have toothed edges. They also smell musty when disturbed or crushed. The tiny flowers collect in rounded clusters. Now that you know what to look for, let’s explore 10 plants that look like poison hemlock and how to identify them.

Angelica

The Leaves of a Great Angelica Plant (Angelica Atropurpurea) Close-Up To See The Patterns And Designs Of The Leaves.

Angelica plants have several differences, including their foliage.

©TippyTortue/Shutterstock.com

Not all poison hemlock lookalikes are poisonous. Some, like angelica (Angelica atropurpurea), have important and helpful purposes. Angelica is a medicinal herb that has played a vital role in several traditional healing systems. It is an herbaceous perennial that reaches the same height (10 feet) and develops white or greenish-white flowers. Unlike poison hemlock, angelica can grow in partially shaded areas. It has purple stems that are usually uniform in color but can have some spots. However, its leaves are not fern-like or lacy and are significantly larger. The most notable and obvious distinction is the lovely scent angelica flowers emit. 

Common Elderberry 

Common elderberry (Sambucus canadensis). Called American black elderberry and Canada elderberry also

While elderflowers are white, they don’t grow in the same cluster shape that poison hemlock flowers do.

©Nikolay Kurzenko/Shutterstock.com

It is not common elderberry (Sambucus canadensis) plants themselves that can cause misidentification. But the elderflowers, which arrive before the berries, can often trip people up. So, a few key things to keep in mind are that elderflowers do not develop in an umbel shape and are significantly larger. The plant is significantly different since it is a shrub or tree that belongs to the Adoxaceae (muskroot) family.

Cow parsnip 

Cow-parsnip (Heracleum maximum) in forest clearing in Shenandoah National Park, Virginia. Only member of the hogweed genus native to North America. Plant reaches more than six feet (3 m) tall.

Cow parsnip looks similar to two toxic plants and should be avoided unless positive identification can be made.

©Gerry Bishop/Shutterstock.com

Another member of the Apiaceae family is cow parsnip (Heracleum maximum). This North American native plant also looks strikingly similar to water hemlock, which is also toxic. Since cow parsnip looks so much like two highly poisonous plants, it should be avoided unless you can absolutely be certain about your identification. The only difference between poison hemlock and cow parsnip is the latter has larger flowers and leaves.

Giant Hogweed 

Heracleum mantegazzianum, commonly known as giant hogweed, is a monocarpic perennial herbaceous flowering plant in the carrot family Apiaceae

Giant hogweed looks strikingly similar to poison hemlock. However, it should also be avoided since this particular plant is also poisonous to people.

©akslocum/Shutterstock.com

The highly toxic giant hogweed (Heracleum mantegazzianum) plant belongs to the Apiaceae family. While its flowers look similar to those on poison hemlock, and it has purple spots on the stems, there are enough differences to tell the two apart. First, the giant hogweed can grow to around eighteen feet tall, so it is much larger than poison hemlock. And everything is much larger about this plant. The flowers can reach up to two and a half feet in diameter. Additionally, its large leaves grow up to five feet wide and are not lacy. However, that doesn’t mean giant hogweed is safe. It can easily cause skin burns, blisters, and blindness when touched.

Queen Anne’s Lace

Queen Anne’s lace flower cap

The Queen Anne’s Lace flowers look very similar to those on the poison hemlock plant. Thankfully, there are enough differences to tell the two apart.

©Lake Erie Gal/Shutterstock.com

Another medicinal herb that often gets mistaken for poison hemlock is Queen Anne’s Lace (Daucus carota), which is also in the Apiaceae (carrot) family. Thankfully, several unique distinctions set this helpful herb apart. First and foremost is its stem and leaves. They are both hairy, in stark contrast to those of poison hemlock. This particular plant is also significantly shorter, reaching only three feet tall at maturity. Additionally, you can spot differences in the flowers upon close observation. The blossoms are flatter, bloom later in the year, and usually have a single darkly colored flower in the mix.

Water Hemlock 

Close up of Water Hemlock (Cicuta maculata). Each flower head is composed of clusters of small, five-petaled white flowers. Photo taken on the Silver River in Ocala, Florida. Nikon D750 with Nikon 200mm Macro lens

Water hemlock is highly toxic to people and animals.

©iStock.com/cturtletrax

Another toxic look-alike is water hemlock (Cicuta spp.), which belongs to the Apiaceae family. This deadly plant has an even higher level of toxicity than poison hemlock. There are four different species, and all are equally dangerous for humans and animals. Their effects will hit in as little as 60 minutes after ingestion. One species, C. maculata, also has a smooth hollow stem with purple stripes. It grows almost as tall (eight feet) and develops round clusters of tiny white flowers. The leaves of water hemlock have distinctive veins that terminate between the individual teeth.

Wild Chervil

white fragrant tender flowers (Anthriscus sylvestris) in summer forest close-up

Even though wild chervil is edible, it is best to leave the plant alone. It closely resembles two poisonous plants and misidentication can be fatal.

©Olena Guzenko/Shutterstock.com

Wild chervil, or cow parsley, (Anthriscus sylvestris), belongs to the Umbellifers family. It grows umbels of small white flowers, much like poison hemlock. However, its leaves are divided and alternate. The flowers and the leaves are significantly larger than poison hemlock, which sets this plant apart. But that’s not the only concern. Cow parsley more closely resembles fool’s parsley (Aethusa cynapium), another poisonous plant. It is slightly less poisonous than poison hemlock, but it will still leave you feeling miserable. Some people enjoy the edible leaves of wild chervil. However, avoid harvesting this plant unless you are 100% certain of its identification.

Wild Fennel

Fennel (Foeniculum vulgare)

While wild fennel looks a lot like poison hemlock structurally, the two have markedly different appearances.

©lzf/Shutterstock.com

Wild fennel (Foeniculum vulgare) is also a member of the Apiaceae family. It is native to the Mediterranean region but is also commonly found in other parts of the world. On the surface, it looks very similar to poison hemlock. The two plants have similar structures and appearances. Thankfully, there are a few notable differences that can help you tell them apart. First is the size. While poison hemlock often reaches ten feet tall, wild fennel doesn’t grow as high. It tops out at around six feet at maturity. Another notable difference is that wild fennel develops yellow blossoms rather than white. This plant also has a licorice-like scent and foliage similar to what you find on dill plants.

Wild Parsnip 

Wild parsnip with leaves displayed

The easiest way to distinguish between poison hemlock and wild parsnip is via its yellow flowers.

©R. A. Nonenmacher / CC BY-SA 4.0 - Original / License

While wild parsnip (Pastinaca sativa) often gets mistaken for poison hemlock, it has a handful of distinguishing characteristics that set it apart. If you can learn to identify it properly, this member of the Apiaceae family can prove highly beneficial. It has edible roots, but getting to them is a challenge since the foliage and stems can burn the skin. Those stems also have grooves, which sets them apart from poison hemlock. Additionally, the flowers of this fascinating plant are yellow rather than white.

Yarrow 

Common yarrow Achillea millefolium white flowers close up, floral background green leaves. Yarrow pattern, milfoil top view. Medicinal organic natural herbs, plants concept. Wild yarrow, wildflower

While yarrow’s flowers are white, they don’t grow in the same shape as poison hemlock flowers.

©SakSa/Shutterstock.com

Yarrow (Achillea millefolium) belongs to the Asteraceae (daisy) family but has enough similarities to poison hemlock that it is easy to mistake the two. One of the most notable similarities is its lovely white flowers. However, yarrow flowers don’t develop in the same umbel. And while the foliage looks slightly similar, yarrow’s leaves are rather frilly and not triangular. The most striking distinction is that yarrow only reaches two to three feet tall at maturity. Understanding the difference between the two is important since you don’t want to miss out on the medicinal benefits of yarrow!


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About the Author

Jennifer Hollohan is a writer at A-Z Animals, where her primary focus is on gardening, mammals, and travel. Jennifer has over twenty years of writing experience. She holds a Master of Arts in Anthropology from the University of Colorado at Boulder, which she earned in 2005, and is a Herbalist. Jennifer lives in Colorado with her family. She loves hiking, admiring wildflowers, gardening, and making herbal tea.

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