top of page
  • Mikl Brawner

Poison, Food & Medicine

By Mikl Brawner:


If you read through the List of Poisonous Plants in Wikipedia and see how many are common in our everyday lives, you might be afraid to garden or even take walks in nature. But humans have interacted with and eaten plants for thousands of years, so let’s be reasonable, but also careful.


Peracelsus, the “father of toxicology” is credited with making this classic statement in the 1500s: “All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison.” Allergies also demonstrate that people differ in their sensitivities. Peanuts are food to some, deadly poison to others. The American Assoc. of Poison Control Centers reported that in 2010, one person died from poisonous mushrooms and two died from poisonous plants; in 2012, seven people died from poisonous mushrooms and two from poisonous plants. Pretty good odds for 330 million people; hopefully this article will improve yours.


Rooted to the earth, plants can’t run away from predators so they defend themselves chemically, producing phytochemicals that act in various ways in their defense. Most common is to make themselves indigestible. Poor digestion can result in stomach cramps or gas—think rhubarb or beans. Other chemical defense strategies make the plant hallucinogenic, repellant, painful to touch, or even fatally poisonous.

Phytochemicals can protect a plant from viruses, bacteria, fungi and parasites, as well as insects, animals, and humans. They can also support the immune systems of animals that eat the plants—think black currants and elderberries. Humans have learned to cook some plants to make them less toxic, more digestible. Raw elderberries can give you a stomach ache, but cooked, they can be an immune-building syrup. And one part of a plant can be food while another is poisonous.

Deadly Nightshade, Atropa Belladonna, plant and berry, which can be black or green.
Deadly Nightshade, Atropa Belladonna plant
Deadly Nightshade, Atropa Belladonna berry, which can be black or green.
Deadly Nightshade, Atropa Belladonna berry, which can be black or green.

Some people are allergic to plants in the nightshade family: tomatoes, potatoes, and eggplants all contain nightshade chemicals. Deadly Nightshade, Atropa belladonna, is a common weed that has little green to black fruits that look a lot like little tomatoes. It is truly deadly; eating 2 berries can kill a child and 10 can kill an adult. Even touching the leaves or stems can cause skin irritation and burning, worse if the sap gets in your eyes or mouth.


When the Puritans brought tomatoes back to N. America, many were afraid to eat it. Colonel Robert Johnson staged a display in the late 1700s, eating a large quantity of tomatoes in front of a crowd. When he didn’t die as expected, the tomato was more accepted as food.


Potatoes can be poisonous if allowed to turn green; always peel or cut out the green parts. Another Nightshade, Goji Berry, has flowers that resemble Deadly Nightshade, but it has become a popular Superfood for improving eyesight and supporting immune function. Tobacco is a Nightshade with toxic phytochemicals. Two cigarettes in a gallon of water was an old-fashioned insecticide.



Poison Hemlock (Conium maculatum) plant
Poison Hemlock (Conium maculatum) plant
Poison Hemlock (Conium maculatum) seedhead
Poison Hemlock (Conium maculatum) seedhead

One of the most poisonous wild flowering plants found in Colorado is Poison Hemlock, Conium maculatum. Also called Water Hemlock and Socrates Hemlock, it grows in moist places from 3400'-8000' in much of the state. The six foot tall plants have large, umbrella-like clusters of small white flowers, and ferny leaves—much like Queen Anne’s Lace. Poison Hemlock stems are smooth with dark purplish splotches, while Queen Anne’s Lace has solid green stems covered with tiny hairs. All parts of the plant are very poisonous, especially the roots. A news report in June shocked the nation with the story of a woman who had to go to the emergency room just from hand-pulling Poison Hemlock.


Monkshood, Aconite
Monkshood, Aconite

Some beautiful, very poisonous plants found in Colorado woodlands and gardens are Monkshood (Aconitum), Delphinium, and Larkspur All parts are extremely poisonous, especially roots, seeds, and new growth. Sold as gardening plants and cut flowers, five species grow wild locally. Touching the leaves can cause skin irritations. Foxgloves (Digitalis lanata) make an important heart medicine, but all are deadly if eaten and skin contact can cause skin irritation or an allergic reaction, especially if the sap gets into a wound or in eyes.


An ornamental that’s designated as a noxious weed is Euphorbia myrsinites, Myrtle Spurge. It has bluish succulent foliage and yellow-green flowers early in Spring. The white milky sap is caustic and can cause eyes to swell shut. An entire preschool was once sent to the emergency room because the children were face-painting with the white sap.


Everybody knows about Poison Ivy’s three shiny leaves, but beware the plant without leaves in winter when it is only recognized by its short stems with white berries. The painful rash can spread over the body and some people have an extreme reaction to it. Poison Sumac and Poison Oak are not found in Colorado, according to Ackerfield’s, Flora of Colorado.

Death Camas
Death Camas

One more poisonous wildflower, Death Camas, blooms in early spring with cream to white flowers on 10"-16" stems. The leaves and bulbs are the most toxic, but are rarely a problem unless mistaken for wild onions. Several popular ornamental bulbs are poisonous, especially Daffodils and Hyacinths, which is why mountain gardeners can enjoy them in deer country. Wash your hands after handling the bulbs and flowers.

Datura (aka Jimson Weed)
Datura (aka Jimson Weed)

I once got a call from a gardener who explained that her eggplant had spikes on the fruits. Datura had gotten mixed in with them - their leaves are similar. It’s good she didn’t try eating them; Datura has a nasty reputation. As one story goes, George Washington’s army was starving in Jamestown, Virginia and the French cook, who didn’t know the local flora, served up large quantities of Datura greens for the troops. They became immobilized for days with hallucinations. Ever since, the plant has been called Jimtown or Jimson Weed.


Many plants are poisonous to cats and dogs. One expert said, “Typically, cats are pretty careful about what they eat, making poisoning relatively rare.” But lilies are very toxic to cats; they may play with the sticky pollen and ingest it while grooming. Extensive lists of plants poisonous to cats and dogs are found at the Germantown Parkway Animal Hospital website.


Children should be warned not to eat any plant, especially berries, that are not from the garden.

Mikl Brawner and his wife Eve own Harlequins Gardens in Boulder, specializing in organic veggies and herbs, natives, sustainable roses, xeriscape, unusual perennials, and products to build healthy soils.

132 views
bottom of page