Between the Rows: Beware of poisonous plants

  • Children eating rhododendron leaves or flowers will get sick, but these plants are not deadly. Contributed Photo/Pat Leuchtman

  • The castor bean plant, recognizable by the large-leafed foliage and red seed cases, can reach a height of 8 feet or more. Contributed Photo/Pat Leuchtman

For the Recorder
Sunday, March 18, 2018

Few of us hear much about castor oil anymore, but my childhood memory is that it was a common laxative or a topic for a joke. As an adult I never gave a thought as to where castor oil came from, so it was with great shock that, when I admired a beautiful big plant with dark red-tinged leaves and prickly red seed cases, it was identified as the poisonous castor bean (Ricinus communis) plant.

I continue to admire castor bean plants, but I would be too nervous to grow it in my garden. Castor bean plants are very poisonous. The poisons are ricin, a toxic protein, and ricinine, an alkaloid. When ingested, the beans will cause serious symptoms including nausea, convulsions, coma and even death.

Like most of us, I don’t often think about whether the plants in my garden are poisonous, but I just read a startling statistic from the 2015 annual report by the National Poison Control Center that “plants were implicated in over 28,000 cases of poison exposures.” That statistic is a warning that if we have pets or young children, we should be aware of the level of danger of some of our favorite plants.

The list of plants that will cause illness and death is much longer than I imagined. I knew that rhubarb leaves were poisonous and should not be eaten, and all parts of the beautiful datura can cause hallucinations, delirium, convulsions and even death. Foxgloves are so toxic that even the water left in a vase holding a foxglove bouquet is toxic.

If you are a reader, you may recall that water hemlock, Cicuta maculata, played a vital part in “A Thousand Acres” by Jane Smiley. Water hemlock is considered the most toxic plant native to North America.

All parts of several familiar and common plants like delphinium, lily of the valley, daphne, monkshood, azaleas and rhododendrons are toxic, and if taken in sufficient quantity can sometimes cause death.

I am fascinated that many creatures are aware of plant poisons and know they must not nibble on them. I got all excited when I was told that rhodendron flowers were toxic to honey bees. I had just planted three rhododendrons! But just in time, I learned that while bumblebees love rhododendron flowers, honey bees have zip interest in them. I can relax and enjoy my rhodies, knowing that visiting pollinators are safe. I don’t think there is anyone else of my acquaintance who might be tempted to nibble at the flowers or foliage.

While we should all be aware of the toxicity of the plants in our gardens, I do not think we need to avoid these plants; we just need to be aware of the dangers. I don’t have children in my garden anymore, nor do I have pets. The squirrels and rabbits who visit must take their chances, but I actually think they are much too smart to eat anything that would upset their little stomachs.

Some houseplants are toxic as well. Cyclamen, spathiphyllum, philodendron, kalanchoe, pothos and scheffleras are all dangerous for cats. Lilies are highly toxic to felines who might nibble on the petals, stamens or even the roots after they knock the vase over.

You can go online to find out about the toxicity of garden plants. Cornell University has a database listing plants poisonous to livestock and other animals like humans at bit.ly/2tMbmQf. I can tell you that the “AMA Handbook of Poisonous and Injurious Plants” by Kenneth Lampe, published by the American Medical Association, and “The Handbook of Poisonous and Injurious Plants” by Lewis Nelson are both available through our local library system.

One of my favorite garden writers is Amy Stewart. An early book she wrote is titled “Wicked Plants: The Weed that Killed Lincoln’s Mother and Other Botanical Atrocities.” This fascinating book tells the story, among others, that you don’t even need to eat a certain plant to have it kill you. Nancy Hanks, Abraham Lincoln’s mother, didn’t eat the Eupotorium rugosum that caused delirium, tremors, weakness and ultimately death. It was the cow she milked that ate the white snakeroot making its milk poisonous. In 1818 when Hanks died, Abraham Lincoln was only 9 years old. Milk sickness was not an unheard of ailment. It was a problem for cows, as well as for those who drank their milk. Areas where the weed grew in pastures even came to be called Milk Sick Ridge and Milk Sick Holler. It was not until the 1920s that the cause of milk sickness was identified.

Stewart’s book is organized by the types and severity of poison plants from deadly and dangerous to painful, and includes the plants that are destructive for the way they can spread and play havoc with the environment. Purple loosestrife and Caulerpa taxifolia, a killer algae, are just a few examples. C. taxifolia is considered one of the worst invaders by the Invasive Species Specialist Group. There are many ways a plant can become dangerous and deadly.

Enjoy your gardens, but beware!

Pat Leuchtman has been writing and gardening since 1980. Readers can leave comments at her website: www.commonweeder.com.