Scientific name: Conium Maculatum
What Is It?
Poison hemlock (Conium maculatum) is an acutely toxic plant that, if ingested, can kill humans and animals within a few hours. It is found in many areas including fields, roadsides, gardens, and trails or in dryer parts of the state, near ditches or other sources of water. A single plant has many seeds, which are spread by animals, water, erosion, and humans.
Is It Here Yet?
Yes. It is found across the country and throughout the entire state.
Why Should I Care?
Poison hemlock easily may be confused with similar-looking edible plants, like carrots, wild parsnips, parsley, and anise. A few hundred grams of leaves can be fatal. Poison hemlock also can be toxic through skin contact or inhalation when mowing large patches of the plant. All parts of the plant are poisonous, and even dead plants remain toxic for up to three years. Call a veterinary clinic or poison control center (800-222-1222) immediately if you suspect an animal has eaten poison hemlock.
How Can We Stop It?
Poison hemlock may be controlled by pulling or digging out the plant, including the entire woody root. Wear gloves before handling the plant, as every part of the plant is toxic. Mowing is less effective, as plants can regrow quickly. Throw poison hemlock plants in the garbage, not in yard waste. Plants still are poisonous when they dry.
What Are Its Characteristics?
- Feathery, fern-like leaves with a strong, musty smell.
- Stem is hollow and green with red-purple spots or splotches, and not noticeably hairy. Can reach 12 feet tall.
- Small white flowers grow in flat-topped, umbrella-like clusters at ends of stems.
- Two-year life cycle with low-growing plants visible most of the first year and taller plants that bloom in May and June during the second year.
- Each plant produces up to 40,000 seeds that sprout throughout the growing season.
How Do I Distinguish it From Native Species?
As a member of the carrot family, it looks very similar to many other family members. The native species, water hemlock, looks similar, but is only three to six feet tall, doesn’t have such feathery leaves, and almost always grows in wet areas and shorelines. Although native, water hemlock is even more toxic than poison hemlock and should never be consumed. Other plants similar to poison hemlock don’t have hairless, purple-spotted stems or are much shorter. Wild carrot or Queen Anne’s lace, for instance, has hairy stems and is not as tall. Water parsley also is much shorter, doesn’t grow as upright, and lacks purple spots on the stems.
Additional Photos
