By Jim Leser
I used to be extremely allergic to poison ivy. I swear that as a child I could literally become infected just by looking at it. This was back east where I was originally from. When I moved to the west I found that poison oak caused the same uncomfortable itch wherever the plant had contacted my skin either directly or secondarily from contaminated clothing. What followed was red, oozing blisters that seemed to spread across my body as I continued to scratch. I couldn’t help myself.
I soon learned that the toxin, urushiol was easily spread if not removed from contaminated clothing or skin through washing. The fluid in blisters did not spread the rash. What is really odd now is that I no longer seem to be affected by poison ivy. I walk by it every time I walk on the Surface Creek trail, which is quite often. Since the urushiol toxin is especially troublesome when released by burning poison ivy plants, I always thought that this toxin was probably released into the air during those suffocating summer days of high temperatures and humidity. But who knows?
Even experienced gardeners sometimes fall prey to plants that can cause pain, misery and, although rare, even death. Some are native species; others, non-native. Each year, people, often children, and sometimes pets and livestock are poisoned or otherwise harmed from toxic berries, bulbs, leaves and other plant parts.
There are many other plants besides poison ivy that can pose a hazard to us, our pets or livestock. What follows is a very brief listing of some of the more common ones you might encounter in the garden, on the trail or out in the pasture.
The parsley family three poisonous plants including cow parsnip, western waterhemlock and poison hemlock. The sap from these plants can cause severe, painful burns and can also make your skin sensitive to sunlight. If the sap comes into contact with someone’s eyes, it can lead to temporary or permanent blindness. The sap in the taproot of the western waterhemlock is extremely toxic to humans and animals. And of course poison hemlock contains a well-known poison historically used to take out one’s enemies. Don’t mistake any of these plants for parsley.
Hazardous plants found in the sunflower family include common or western and giant ragweed. These are considered the number one cause of hay fever, in part because of their abundance and the fact that it flowers all summer long. Russian Knapweed is a thistle in the sunflower family that affects horses making them unable to chew if ingested.
The nightshade family has a number of poisonous plants including Virginia groundcherry, bittersweet or climbing nightshade and silverleaf nightshade. Leaves and berries can be quite toxic to humans, cattle and horses if ingested in sufficient quantity. Children can be particularly attracted to the berries which will cause poisoning if eaten in sufficient quantity. The Virginia groundcherry has attractive flowers Chinese lantern-like seed fruit which can be quite attractive. I found these nightshade plants along my irrigation ditch. I guess you know that both potatoes and tomatoes are in this plant family. Thank goodness they are not poisonous.
Another nightshade representative is sacred datura. It has large, attractive white flowers and unusual large round seedpods covered with spines much in the manner of a medieval mace. All parts of the plant and especially the seeds contain many alkaloids, the most toxic of which are hyoscyamine, hyoscine and atropine. The principle effect of these alkaloids is on the autonomic nervous system. The plant is generally not consumed by livestock except when other food in not available. It also has hallucinogenic properties. Among the Zuni people, the powdered root is given as an anesthetic and a narcotic for surgery. Sacred datura has also been used by some Native Americans in ceremonies and rites of passage. I would not recommend “tripping” on this plant!
Leafy spurge, of the spurge family, was introduced from Europe and is an invasive noxious weed. Diterpene esters in the milky sap are strong irritants causing blistering of the skin in some humans who handle the plants. Salivation, vomiting and diarrhea may result from irritation to the digestive tract if ingested.
Of course, most plants are beneficial and perfectly benign, but hazardous plants, though much fewer in number, are found everywhere. Readers, take heed: wear gloves, don’t eat strange berries, educate your kids and remove hazardous plants that are a risk to you and your pets.
Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.