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 dessert 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 a 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 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.

Asclepias (milkweed)

Asclepias (milkweed)

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), 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), mayapple 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.

Good resource for poisonous plants: Wikipedia List of Poisonous Plants