Things to know when a-foraging you go
“All plants are edible. Some of them only once.” – Anon.
If you’re delving into the world of wild edibles or other wilderness activities, you need to know which plants have the distinction of being hazardous to your health.
These dangerous plants can come in many forms, ranging from mild skin irritants to deadly poisons.
Fortunately for us, there are very few lethal plants in southern Manitoba. Unfortunately, dangerous plants don’t always look dangerous – in fact, some bear a striking resemblance to those that are perfectly safe.
Canada moonseed (Menispermum canadense), for example, is a vine that not only looks like our edible wild grape (Vitis riparia), it often intermingles with it. Getting the two confused has resulted in convulsions or seizures and even death. Luckily, if we pay closer attention, we can easily distinguish between the two. (More on telling plant friends from plant foes below.)
The toxic compounds in most of Manitoba’s poisonous plants are broadly grouped as alkaloids, glycosides, oxalates, resins/resinoids and alcohols. However, not all compounds that fall under these categories are toxic. In fact, many are common medicines.
Alkaloids are complex nitrogen-containing bases (the opposite of acids) that are known for a wide range of physiological effects on humans. They include common drugs such as nicotine, morphine and quinine, as well as notorious poisons like strychnine. Canada moonseed, which grows along river banks in Manitoba, contains several alkaloids, including berberine, menipine, menispermine and dauricine, but dauricine is the principle toxin.
Among the glycosides is salicin, an alcoholic glycoside found locally in the inner bark of willows (Salix spp.). When ingested, enzymes convert salicin to salicylic acid, which functions much like aspirin (aka acetylsalicylic acid, or ASA), similarly reducing pain, swelling and fever. Cardiac glycosides, like the apocynamarine found in our local dogbane species (Apocynum spp), affect the contractile tissues of the heart. When carefully prescribed, as with the commercial heart medication derived from foxglove (Digitalis purpurea), cardiac glycosides can stimulate heart function. But when carelessly or accidentally ingested, they can overstimulate it to the point of heart failure. Though no human poisonings from dogbane have been reported, it is said that a mere half ounce of the dried leaves could kill a large farm animal. To be on the safe side, make sure you can tell the difference between the potentially poisonous dogbanes and their harmless and tasty lookalike, milkweed, before you proudly prepare the steamed greens for your family dinner!
Oxalates are a group of carbon-based acids routinely produced by plants and animals. Plants in the Arum family (Araceae), such as jack-in-the-pulpit (Arisaema triphyllum), are well-known for their calcium oxalate content. When ingested, the needle-like crystals cause intense irritation of the mouth and throat. I remember one person telling me how, while on a canoe trip, he plucked an “edible-looking” plant from the shoreline and ate it. “I immediately felt like I had thousands of razor blades in my mouth and going down my throat. I didn’t know what was happening – I was freaking out,” he told me, as he relived his eye-opening encounter with a perfectly innocent-looking poison. The adverse effects of mistakes like this can last up to two weeks and may include damage to the digestive tract and kidneys.
Resins and resinoids are secreted from the wounds of certain plants as protection against insects and fungi. On one end of the safety spectrum is spruce sap or pitch, which exudes from cut branches or holes made by sapsuckers. It is known for its antimicrobial properties and its ability to promote healing. Some people even chew it as gum. On the other end of the spectrum is urushiol, the oily substance found in poison ivy, poison oak and some sumac species. Urushiol is highly allergenic, affecting 50 percent of people to varying degrees. Ingesting the plant or its berries – even inhaling the smoke from burning poison ivy – can cause internal distress, including irritation to the nose, throat and lungs, changes to white blood cells and abnormal liver function. Surprisingly, some animals actually eat poison ivy, and I have occasionally seen small patches denuded of their leaves by deer. For some birds, the off-white berries are a culinary treat.
You may be relieved to know that, contrary to popular belief (and diagnoses by local doctors), poison oak does not grow in Manitoba. In fact, poison oak occurs only in coastal regions, from New Jersey southward and from B.C. down to Mexico. Poison oak doesn’t even look like an oak tree; it’s very similar in appearance to poison ivy, though the leaves may be more deeply lobed.
Natural alcohols are common in plants, though very few have toxic effects. Cicutoxin, an alcohol found in water-hemlocks (Cicuta spp), has given these species the notorious reputation of being the most poisonous in North America. Ingesting only a small amount can cause violent tremors, intense stomach pain, salivation, delirium and, finally, death. With careful observation of mature plants, the most common water-hemlock in southern Manitoba, Cicuta maculata, can be distinguished from the edible water-parsnip (Sium suave). That said, I have noticed that the first few leaves put out in the spring (the time of year for gathering edible roots from water-parsnips and other plants) are sometimes indistinguishable between the two species. So, if someone tells you water-parsnip roots are to die for, I suggest you don’t take them literally.
Before heading out to sleep in a pile of leaves or gather a basketful of wild plants to fortify your next meal, I strongly suggest you get to know the hazardous plants in your area first. Find out which edible plants have poisonous lookalikes and learn how to tell them apart. Two books in the Peterson Field Guide series are a great place to start. A Field Guide to Edible Wild Plants depicts edible plants and poisonous lookalikes side by side, with a skull and crossbones indicating the one to be cautious of. A Field Guide to Venomous Animals and Poisonous Plants provides details on the toxic chemicals found in plants, along with the symptoms and mode of action.
With a bit of research, you can put your mind at ease and head out into the wild, confident in the knowledge of which plants can feed you, heal you or simply delight you, and the rare few that can quickly take the fun right out of everything.
The founder of Prairie Shore Botanicals, botanist Laura Reeves regularly shares her enthusiasm for wild edibles, wilderness skills, urban survival and disaster preparedness in courses, workshops and private consultations. Laura also sells sustainably wild-harvested herbs and is helping to restore 100 acres of tall grass prairie within the Manitoba Tall Grass Prairie Preserve. For more info, visit psbotanicals.com and like Prairie Shore Botanicals on Facebook.