If you or someone you know forages for wild plants, please watch out for poison-hemlock. It is in the same family as carrots and parsley and many other edible plants, but can be fatal when eaten. Unfortunately, poison-hemlock is commonly found growing around community gardens and p-patches and along public trails. Once I even found a poison-hemlock growing right in a bed of carrots.
Poison-hemlock leaves and roots resemble carrots but can be distinguished by looking closely. Poison-hemlock stems always have some amount of red or purple spotting on them, even when young.
The roots are not orange like a carrot, but rather yellowish or dirty white in color.
Also, carrot leaves and stems are somewhat hairy but not poison-hemlock, which has smooth stems and leaves. In fact, poison-hemlock leaves often look shiny, especially compared with carrot leaves.
Poison-hemlock also gets much larger. The leafy clumps can be a couple of feet tall in the early spring and the plants grow 4 to 8 feet tall when in flower.
And if smell is your best sense, you will notice that poison-hemlock has a distinctively unpleasant musty smell.
There are scary poison-hemlock stories just about every year. A couple of years ago, our office received a phone call from someone who stopped a woman from eating poison-hemlock while he was out walking on a trail in Seattle. He couldn’t speak her language and isn’t sure if she really understood him, but at least she stopped collecting the leaves. In another near miss, my daughter’s old elementary school had a scare when they realized there was poison-hemlock growing through the playground fence where the kids were playing, and not far from their school garden. There are even scarier stories where people actually ingested poison-hemlock and became seriously ill or even died, as in the cases in 2010 from Bellingham and Tacoma. A 2015 article in Food Safety News sums up the problems and the worries very well.
Even if you don’t have any poison-hemlock near your own garden, please help others by letting them know if you see any. This is especially important in p-patch or community gardens where new gardeners or newcomers to our area may be unfamiliar with this plant. In public parks or on trails, you can contact the local parks department and encourage them to remove the plants where they are most accessible to people who might be harvesting wild plants for food.
Poison-hemlock is acutely toxic to people and animals, with symptoms appearing 20 minutes to three hours after ingestion. All parts of the plant are poisonous and even the dead canes remain toxic for up to three years. The amount of toxin varies and tends to be higher in sunny areas. Eating the plant is the main danger, but it is also toxic to the skin and respiratory system. When digging or mowing large amounts of poison-hemlock, it is best to wear gloves and a mask or take frequent breaks to avoid becoming ill. A few years ago, a woman described to me a severe reaction she had after pulling plants on a hot day. It seems that the toxins were absorbed into her skin.
The typical symptoms for humans include dilation of the pupils, dizziness, and trembling followed by slowing of the heartbeat, paralysis of the central nervous system, muscle paralysis, and death due to respiratory failure. For animals, symptoms include nervous trembling, salivation, lack of coordination, pupil dilation, rapid weak pulse, respiratory paralysis, coma, and sometimes death. For both people and animals, quick treatment can reverse the harm and typically there aren’t noticeable aftereffects. If you suspect poisoning from this plant, call for help immediately because the toxins are fast-acting – for people, call poison-control at 1-800-222-1222 or for animals, call your veterinarian.
In King County, poison-hemlock falls into the category of noxious weeds that are so widespread in the county that control is not required, although agencies and property owners are encouraged to remove it if possible or at least keep it out of areas that are accessible to people or animals. Other counties in Washington do require control of poison-hemlock, so be sure to call your local noxious weed board to see what rules apply in your area.
If you have poison-hemlock, it can be effectively controlled by manual or mechanical methods – pulling or digging up small plants, cutting below the crown for large plants, or repeated mowing starting in early April. Always use gloves when handling and wear a mask or take frequent breaks when mowing large patches. Chemical control can work too but be careful not to kill grass that can help suppress weed seeds from germinating and follow all safety and use directions on the herbicide you use.