“‘Herb Teacher Poisons Students,’ I can see the headlines now,” she said with exasperation in her voice, as she gestured at the newly sprouted green plants in front of us. ” You tell me one of these plants here is poisonous and the other is edible and nutritious. Here they are growing right beside each other. I’m an herbalist and I can’t tell them apart! How am I supposed to teach my students if I can’t even figure them out? “
It was mid-May at an herb conference in Massachusetts. A group of us were on an herb walk and we were exploring an open field where we found young shoots of dogbane, Apocynum cannabinum, growing intermixed with common milkweed, Aesclepias syriaca.
Milkweed shoots at this time of the year are edible and delicious as a cooked green vegetable or pot herb. They can be cooked by dropping the fresh picked shoots in a pot of boiling water and simmer them for 20-30 minutes, until tender. I’ve eaten many a “mess” of these tender milkweed greens and I find them delicious and well received by anyone I serve them to.
Dogbane, however, is highly toxic. It contains the cardiac glycoside, apocynamarine, which can cause cardiac arrest. As little as half an ounce of the dried leaves mixed in hay can kill a large farm animal. (Dogbane is also known as Indian hemp because the mature stalks yield a fine hemp-like cordage or textile fiber.)
When these plants are mature they are easy to tell apart by their distinctive flowers and seeds. The milkweed stem becomes thick and hairy while the dogbane stem is more slender and takes on a reddish hue. But these plants we were looking at here were hardly a foot tall. Both species have opposite, oval leaves and both plants exude a white, milky latex when the leaves are broken. At this time of the year they were almost identical.
These herb enthusiasts wandered around the field getting very confused and discouraged. I could tell the difference between the two species, but I have been studying these plants for a number of years. I kept trying to point out the subtle differences, like the more robust structure of the milkweed, but it was almost impossible to convey the differences especially when we could find a delicate, young milkweed shoot with a slender stem next to a large, older, thick-stemmed dogbane. Many of these folks were experienced with plants and it was disheartening to think that a group like this could not positively differentiate between a common edible wild plant and its highly poisonous look-alike.
Finally someone piped up, “Did anyone taste them? We need to let our whole body speak. What do they taste like?” We started tasting and within a few minutes we all could agree the milkweed leaves were mild and chalky tasting while the dogbane leaves were powerfully bitter and acrid. The difference was clear as could be. Using our taste buds there was no mistaking the poisonous plant. It was also comforting to realize that in this instance the toxic plant was much too bitter to eat.
We all learned an important lesson that day. Identifying plants is not a dry intellectual exercise using only our brains, our eyes and our field guides. To identify plants effectively we must use our other senses as well–touch, taste and smell. Identifying plants at its best is a whole body, holistic experience that can deepen our connection with the plants and the world in general in many ways.
Is it dangerous to put poisonous plants in our mouths? Most experts agree that a small amount of any wild plant (and even deadly mushrooms) can be tasted and spit out with no adverse effects. (The exceptions might be dermatitis causing plants like poison ivy and nettles.) This does not mean that all poisonous plants taste bad. Some deadly mushrooms and poisonous members of the carrot family, like the highly toxic water hemlock, are mild and pleasant tasting. So as you explore wild plants, use your senses but also use your head and your good common sense as well as your reference materials. Enjoy the taste, touch, smell, the visual beauty, as well as the intellectual stimulation that this rich, complex, miraculous, green world that surrounds us provides.
Speaking of edible wild plants, Sam Thayer has done it! He has produced the most comprehensive field guide to the edible wild plants of eastern North America ever written. He covers 700 edible species. If you’re interested in edible wild plants anywhere east of the Rockies, this is the book for you. Truly a masterwork!