Mackenzie’s Water Hemlock: A Beautiful but Deadly Native You Should Never Plant
When it comes to native plants, most deserve a place in our gardens and hearts. But Mackenzie’s water hemlock (Cicuta virosa) is the exception that proves the rule. This northern native may look innocent with its delicate white flowers, but don’t let its pretty appearance fool you – this is one plant you definitely don’t want anywhere near your garden, your family, or your pets.
What is Mackenzie’s Water Hemlock?
Mackenzie’s water hemlock is a perennial forb native to the cold regions of Alaska and Canada. Also known by its synonym Cicuta mackenzieana, this plant belongs to the carrot family and shares some visual similarities with other members of this group. It’s classified as an obligate wetland species, meaning it almost always grows in very wet conditions.
As a forb, this plant lacks significant woody tissue and dies back to the ground each winter, regrowing from its root system the following spring. But here’s the crucial point: every part of this plant – from its innocent-looking white flowers to its underground tubers – contains deadly toxins.
Where Does It Grow?
You’ll find Mackenzie’s water hemlock throughout northern North America, including Alberta, British Columbia, Alaska, Manitoba, Ontario, Quebec, Saskatchewan, Yukon, and the Northwest Territories. It thrives in wetlands, along stream banks, in marshes, and other consistently moist areas.
Why You Should Never Plant This Native
Here’s where we break from our usual native plant enthusiasm: Cicuta virosa is considered one of the most poisonous plants in North America. Even small amounts can be fatal to humans and animals. The toxins, called cicutoxins, affect the nervous system and can cause:
- Violent seizures
- Respiratory failure
- Death within hours of ingestion
- No known antidote
The plant is particularly dangerous because its tubers can be mistaken for edible roots, and even experienced foragers have fallen victim to this deadly look-alike.
What Does It Look Like?
Mackenzie’s water hemlock can grow 3-6 feet tall and produces small white flowers arranged in umbrella-like clusters called umbels. The leaves are compound and divided, giving the plant a delicate, almost fern-like appearance. During its growing season, it creates dense patches in wet areas.
While the flowers might attract some pollinators, any potential ecological benefits are far outweighed by the serious safety risks this plant poses.
If You Encounter It in the Wild
If you come across what you suspect might be Mackenzie’s water hemlock in its natural wetland habitat:
- Never touch or handle the plant
- Keep children and pets well away
- Don’t attempt to remove it yourself
- Contact local land management authorities if it’s in a public area where people might encounter it
Better Native Alternatives for Wet Areas
If you’re looking to add native plants to wet areas of your landscape, there are many safer alternatives that provide similar ecological benefits without the deadly risks:
- Wild bergamot for pollinator-friendly flowers
- Blue flag iris for wetland beauty
- Cardinal flower for stunning red blooms
- Swamp milkweed for monarch butterfly support
The Bottom Line
As native plant enthusiasts, we usually encourage growing indigenous species. But safety must always come first. Mackenzie’s water hemlock is one native that belongs only in its natural wild habitat, far from gardens, homes, and anywhere people might accidentally encounter it.
Remember: not every native plant is garden-appropriate. When it comes to Cicuta virosa, admire its role in northern ecosystems from a very safe distance, and choose one of the many other beautiful, safe native alternatives for your own landscape instead.
