Invasive poison hemlock a growing concern on Vancouver Island

Harmful invasive plants cropping up on the island As summer weather brings residents and tourists into the great outdoors, experts are warning about the presence of potentially harmful plant

Greater Victoria officials are putting out a warning about a non-native invasive plant species that can cause serious injuries if humans touch it.

The Capital Regional District recently issued an alert sheet for poison hemlock (Conium maculatum).

The plant is "a priority invasive species of concern with serious human and animal health risks from ingestion or skin contact," the alert sheet says.

"Originally from Europe, poison hemlock is now found in locations across Canada. In the Capital Region, we are seeing a significant increase in new sites, particularly in locations where soil has been brought in”.

Poison hemlock has seen major growth this year, according to Dr. Glenn Harris, senior manager for the CRD's Environmental Protection Divison.

"We’re seeing it reported all over the Capital Regional District as well as all up the island," he said.

Poison hemlock contains toxic alkaloids, including confine that causes respiratory failure in people and animals when ingested.

All parts of the plant are poisonous to people and even dead plants can remain toxic for up to three years. The seeds contain the highest concentration of poison. The conium alkaloids are volatile and can even cause toxic reactions when inhaled.

Direct skin contact may cause a sunburn-like reaction that could reoccur for years when exposed to sunlight. More alarming though is that if poison hemlock is ingested, even in small amounts, it can be fatal.

Poison hemlock belongs to the same plant family (Apiaceae) as carrots, parsnips, fennel and dill. The plants are often mistaken for angelica, cow parsnip, wild parsnip, wild chervil, wild celery and Queen Anne’s lace.

The plant grows 1.5-2.5 meters (5-8 feet) tall and has a smooth, green, hollow stem.

“It is one off the easiest plants to recognize,” said Ken Marr, a curator of botany at the Royal BC Museum.

“The leaves may look superficially like parsley to you. It will have a cluster, like an umbrella shape, of white flowers. But the number one feature to recognize is it has purple blotches on the stem. Once you see that, you know it’s poison hemlock.”

Each hemlock plant produces thousands of seeds and can spread quickly if not dealt with properly.

Special precautions should be taken to avoid contact when removing the plants from your yard, said Harris.

“People should be using gloves, eye protection, long sleeves and pants, when removing them."

He asked that the plants be put in a garbage bag labeled “invasive plants” or “noxious weeds,” then taken to the Hartland Landfill for proper disposal.

"Do not compost it in your backyard, place it in your green composting bin for pick up and don’t group it off at your municipal garden waste site. This will just continue the cycle of the plant spreading," he said.

Burning the plants is not a good option for disposal because the smoke can become toxic, he said.

The CRD along with local municipalities have taken a joint approach to the problem of invasive plants.

The Capital Regional Invasive Species Partnership (CRISP) aims to coordinate efforts to control and eliminate invasive plants in the region.

“What we are hoping to do is try to get on it early. So early detection and removal is a big part of it," said Harris. "We’re hoping with things like poison hemlock we will get on it quickly and remove it before it starts to spread.”

If you find poison hemlock on your property you should try to remove it as soon as possible. If you are not comfortable doing it yourself, call a professional gardener or landscaper for help.

You can also help by reporting poison hemlock or other invasive plants to your local municipality, CRISP or other invasive species organizations.

There is also an app available called “Report-A-Weed” that people can download and use to report invasive species.

If you are not sure what a particular weed is, there are a number of websites that can help identify them including:

If you or someone you know comes in contact with poison hemlock and you are not feeling well, seek immediate medical attention.