Many of our most beneficial herbs are also very poisonous. Many of our most prized ornamental plants are, too.
An example is oleander. This old-fashioned, flowering, landscape shrub is definitely poisonous. I have read that even the smoke from burning oleander is dangerous. However, I have never known of anyone having health problems caused by this very ornamental plant.
Other common ornamentals like azalea, daffodil, hyacinth, iris, larkspur, narcissus, poinsettia, elephant ear and wisteria are poisonous or have poisonous parts.
All members of the nightshade family are said to be poisonous.
Belladonna or deadly nightshade (Atropa belladonna) is in this family. A few centuries ago, ladies used a distillation of this herb to dilate the pupils of their eyes in order to look more glamorous. This dangerous practice has ceased, but belladonna is now used by the medical profession to dilate pupils for certain eye-care procedures. This herb is a source of atropine and scopolamine, two very important medications that should be used only when ordered by a physician. This is a good example of a deadly plant that is also beneficial.
Jimsonweed (Datura stramonium) is another source for atropine and scopolamine, and another very poisonous herb. When I was a child, jimsonweed grew in a certain area of our hog pasture. The hogs would not go near it. (Do hogs have more common sense than humans?) A few years ago, the seed of jimsonweed were in great demand on the black market. People were consuming it in some manner to take a trip to fantasy land. For some of them it was a one-way trip.
I understand jimsonweed is used in some religious rituals, but I’m inclined to think it should only be used as a medication with a doctor’s supervision.
Castor beans (Ricinus communis) are another common landscape plant. They are beautiful with their large green and maybe red-veined leaves with clusters of green or red seed pods. Children often swallow the seed and suffer a very toxic reaction – sometimes even fatal. I warn you to very carefully protect your children from this beautiful, but deadly, herb, which also provides a valuable medication – castor oil.
Foxglove (Digitalis pupurea) is yet another commonly-grown ornamental herb with both good and bad traits. From this plant we get the wonderful drug digitalis, which slows down, strengthens and regulates the heartbeat. During my nursing days, I encountered a few patients who said, "I increased my dosage of digitalis thinking it would help me." This is a no-no! Always take digitalis exactly as prescribed by your doctor. If problems arise, seek your doctor’s advice. Do not alter your digitalis dosage yourself.
Of course, digitalis and many other herbal medicines have been chemically-cloned, but some doctors still prefer the old-fashioned real-herb variety.
Two of my favorite garden herbs are tansy (Tanacetum vulgare) and shoofly (Nicandra psallioides). Both are poisons. I used to grow tansy, a perennial plant, for its beautiful golden flowers that dry well for crafts. It also serves as a control for ants, fleas, moths and flies. Even though there are recipes calling for the use of tansy, I strongly advise you not to eat this herb, which sometimes causes a severe body rash.
Shoofly is a reseeding annual that produces lovely bell-shaped blue flowers. It is an excellent aid in the eradication or control of flies, especially whiteflies.
This column could go on and on with a long list of herbs with both good and bad traits, but I’ll only mention one more. Since the yew trees of our Northwestern United States have been practically destroyed, it has been found this poisonous plant might produce a medication capable of curing or arresting some types of cancer.
I firmly believe all plants have a beneficial purpose. For many, of course, we have yet to find a use.
Check with your doctor before taking any herbal nutritional products.
*This article was originally written in 1992 and I no longer have an herb garden.