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This post was originally posted on another defunct blog.



Rhododendron—beautiful but poisonous—so are the cousin plants azaleas and laurel shrubs.
When I was a preteen, can’t remember my exact age, I caught a bad case of poison ivy, most likely from walking in the woods. I was miserable for two weeks, and literally covered head to toe in red, blistered, and oozing skin to the point I was physically ill. By the time I recovered, I was very careful to look about me when in the wild for those leaves of three. For years I suffered hypersensitivity to the plant, but now, not so much. I’ve known others who could walk through the stuff in shorts and pull the vines from trees with their bare hands with no effect. Since becoming a garden enthusiast, I’ve learned all those sappy or scent-laden plants can pose dangers to certain people.

While individuals quickly learn any fruit and vegetable they are allergic to, they are often less aware of the dangers in their yards, flower gardens, or inside among the houseplants. Some plants are fatally poisonous; others just make a person very ill, or cause severe dermatitis. Most gardeners know the ‘dangerous’ plants, those so poisonous they watch their grandchildren don’t pick or eat them. Any of these plants can be fatal: caster bean seeds, the twigs and leaves of cherry trees, delphinium, foxglove (digitalis), hemlock (looks similar to queen ann’s lace), jasmine berries, all parts of the jimson weed, larkspur (the annual delphinium), aconitum or monkshood, oeleander berries, and the leafy parts of rhubarb and tomatoes. Yet, do home owners know the ubiquitous yew shrub in their landscaping can also be fatally poisonous?

These are often the most toxic plants, mostly due to the various alkaloids they produce. Other plants, which most gardeners don’t expect to cause trouble, do. Plant parts like the bulbs of many of those lovely spring flowers including daffodils and hyacinth. The milky saps from certain plants like milkweed can cause skin problems for some people. Another hazard? Scent. A vase containing Stargazer or Casa Blanca lilies with their strong, sweet smell, can induce migraines in susceptible people (me). The best way to prevent accidental problems is to know your plants. One of the best sources I’ve found for poisonous garden plants is North Carolina State University’s Poisonous Plants web pages. Michigan State University has a downloadable file of 21 of the most hazardous native or wild plants. While both list only local varieties for their local, these plants are common to many other areas.

A few years ago, I was a member of a floral design club and needed to pick plant materials for a design. As always, I was late putting my design together. I cut some globeflowers (Trollius x cultorum) from my yard and some donkey’s tail sedum (Sedum morganianum) stems from a houseplant. The design designation that day was an underwater design and both plant materials held up very well. After eating the desert served at the meeting, my tongue felt like I’d eaten too much pepper. I didn’t think a thing about it except it was an unusual cake.

By the time I returned home a few hours later, my mouth and face had swollen. I could hardly see. The effects lasted for twelve hours. After some reflection and a call to the hostess, I realized I didn’t have an unknown food allergy but had reacted to the milky sap from the cut ends of the sedum used in my design.

Gardeners should remember that a plant they handle with impunity might cause someone else a health problem. Anyone can have sensitivity to any plant, and their reaction can range from mild to severe as with poison ivy and oak–some people severely react to the plant’s touch and some don’t react at all.

Most gardeners finding poison oak or ivy in their garden take special care not to touch it while eradicating it, yet they are often unaware of other potentially dangerous plants they grow. Since most gardeners enjoy showing their gardens to family and friends, and flowering or fruiting plants often attract very young children, it is wise to know the plants most likely to cause trouble.

Reactions from plants can vary from a mild skin irritation from casual contact, to death from ingesting plant parts. Leaves, stems, roots, rhizomes, tubers, berries, seeds, any part might cause harm, and some safe to eat ripe fruits come from plants with poisonous parts such as cherries and tomatoes.

In my area, the following plants are the most likely culprits to cause skin irritation, aggravate a skin allergy, or cause severe discomfort if eaten: Tree-of-Heaven (Ailanthus altissima), Jack-in-the-pulpit (Arisaema triphyllum), sap of milkweed including butterfly weed (Asclepias species),

Asclepias (milkweed)

Asclepias (milkweed)

Boxwood (Buxus sempervirens), autumn crocus (Colchicum autumnale), Daphne (Daphne species–only a few are hardy in zones 4 and 5), bleeding-heart and Dutchman’s breeches (Dicentra species), cushion spurge (Euphorbia polychroma), ivy (Hedera species), sneezeweed (Helenium species).

Helleborus (Christmas Rose)

Christmas rose (Helleborus species), hyacinth bulbs (Hyacinthus species), St. John’s wort (Hypericum perforatum), iris rhizomes or roots (Iris species), mountain laurel (Kalmia latifolia), lantana (Lantana species), privet (Ligustrum species), lobelia (Lobelia species), lupine (Lupinus species), daffodil bulbs (Narcissus species), flowering tobacco (Nicotiana species), star-of-Bethlehem (Ornithogalum umbellatum), cherry leaves and twigs (Prunus species), oak leaves and acorns (Quercus species), buttercups (Ranunculus species), rhubarb leaves (Rheum species), Soloman’s seal (Polyhgonatum species), bloodroot (Sanguinaria canadensis) azaleas and rhododendron (Rhododendron species).

Sanguinaria (bloodroot)

The following plants can cause severe discomfort or death if eaten even in a small amount: Monkshood (Aconitum napellus), baneberry (Actaeca rubra or A. alba), jimsonweed and moonflower seeds (Datura species), delphinium and larkspur (Delphinium species), foxglove (Digitalis species), may apple except fully ripened fruit (Podophyllum peltatum), pokeweed (Phytolacca americana), castor bean (Ricinus communis), yew (Taxus species).


Digitalis (foxglove)

This is by no means a comprehensive list and only meant to bring awareness, not to make you stop growing a particular plant. These dangers are true of houseplants also, so be careful. I’ve a related post on Seven Night Writers blog of the most deadly plants.

Good resource for poisonous plants: North Carolina State University’s Poisonous Plants



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