Poisonous Plants in the Home Landscape
The list of selected landscape plants with known toxicity tells which part is poisonous and whether people are affected through contact or ingestion.
Last Updated: 12/19by Cheryl Moore-Gough, Extension Horticulture Specialist
MOST PEOPLE KNOW ENOUGH NOT TO TOUCH OR
eat poison ivy. Most ranchers understand that death camas, water hemlock, white loco and some other range plants can cause serious loss of livestock when grazed.
But how many Montana homeowners know that some common ornamentals can cause serious illness or even death if ingested? This discussion is not meant to frighten but to inform and will be particularly helpful in households where small children are allowed to roam freely over the property. Most toxic ornamentals are beautiful plants that deserve a place in the landscape. They also deserve respect. Understand what they can do if misused; then enjoy their beauty throughout the year.
The following plant list is not all-inclusive. New cultivars of some plants may be developed that are less (or more) toxic than the parent species. Some people may develop an allergic reaction to plants that are harmless to most other people. For example, some people go into shock after eating peanuts. Further, the effects of poisonous plants range from slight skin irritation to illness or death. What will actually happen depends upon the inherent toxicity of the plant, the parts contacted or ingested (leaves, stems, fruit, bark), the time of year, stage of growth, the amount of material with which the person has come into contact and the age, weight and sensitivity of that person.
If someone has ingested a poisonous plant, keep him or her calm and warm. Call the Montana Poison Center at 1-800-222-1222 and take a specimen of the suspect plant material with you to the hospital.
Many range plants not commonly found around the home landscape are also toxic. See MSU Extension Bulletin 122, Range Plants of Montana, for more information on toxic range plants.
Daffodil (Narcissus spp.) BY CHERYL MOORE-GOUGH
Larkspur (Delphinium spp.) BY CHERYL MOORE-GOUGH
Bleeding Heart (Dicentra spp.) BY CHERYL MOORE-GOUGH
Plant Parts that are Toxic if Ingested
| Any Part | Fruits, berries | Seeds | Leaves | Roots, bulbs, rhizomes |
| Azaleas (Rhododendron spp.) | Buckthorn (Rhamnus spp. [syn. Frangula]) | Black locust (Robinia pseudoacacia) | Boxwood, common (Buxus sempervirens) | Columbine (Aquilegia spp.) |
| Bittersweet (Celastrus scandens) | Cherry, ground (Physalis spp.) (unripe) | Buckeye (Aesculus spp.) | Buckeye (Aesculus spp.) | Comfrey (Symphytum spp.) |
| Bleeding heart (Dicentra spp.) | English ivy (Hedera helix) | Burning bush (Euonymus spp.) | Cherry (Prunus spp.) | Crocus, autumn (Colchicum autumnale) |
| Christmas rose (Helleborus niger) | Ginkgo (Ginkgo biloba) | Cherry (Prunus spp.) | Cherry, ground (Physalis spp.) | Daffodil; Jonquil (Narcissus spp.) |
| Dutchman’s breeches (Dicentra cucullaria) | Golden chain tree (Laburnum anagyroides) | Four o’clocks (Mirabilis spp.) | Comfrey (Symphytum spp.) | Four o’clocks (Mirabilis spp.) |
| Elderberry (Sambucus spp.)1 | Juniper (Juniperus communis, J. virginiana) | Foxglove (Digitalis purpurea) | English ivy (Hedera helix) | Hyacinth (Hyacinthus spp.) |
| Horsetail (Equisetum spp.) | Mock orange (Philadelphus spp.) | Horse chestnut (Aesculus spp.) | Foxglove (Digitalis purpurea) | Iris (Iris spp.) |
| Larkspur (Delphinium spp.) | Nightshade (Solanum spp.) | Larkspur (Delphinium spp.) | Horse chestnut (Aesculus spp.) | |
| Laurel (Kalmia spp.) | Potato, Irish (Solanum tuberosum) | Morning glory (Ipomoea spp.) | Horseradish (Armoracia rusticana) | |
| Lily of the valley (Convallaria majalis) | Virginia creeper (Parthenocissus quinquefolia) | Peas, sweet (Lathyrus odoratus) | Hydrangea (Hydrangea spp.) | |
| Lupine (Lupinus spp.) | Yew (Taxus spp.) | Plums (Prunus spp.) | Plums (Prunus spp.) | |
| Rhododendron (Rhododendron spp.) | Privet (Ligustrum spp.) | Rhubarb (Rheum rhabarbarum) | ||
| Scotch broom (Cytisus scoparius) | Wisteria (Wisteria spp.) | Tansy (Tanacetum vulgare) | ||
| Wormwood (Artemisia spp.) | Tobacco (Nicotiana spp.) | |||
| Tomato (Solanum lycopersicon) | ||||
| Yew (Taxus spp.) | ||||
| Twigs | Flowers | Bark | Misc | |
| Black locust (Robinia pseudoacacia) | Buckeye (Aesculus spp.) | Black locust (Robinia pseudoacacia) | Sprouts - Black locust (Robinia pseudoacacia) | |
| Boxwood, common (Buxus sempervirens) | Crocus, autumn (Colchicum autumnale) | Buckthorn (Rhamnus spp. [syn. Frangula]) | Buds - Hydrangea (Hydrangea spp.) | |
| Foxglove (Digitalis purpurea) | Cherry (Prunus spp.) | Nuts - Acorn (Quercus spp.) | ||
| Horse chestnut (Aesculus spp.) | Hydrangea (Hydrangea spp.) | Green portion - Potato, Irish (Solanum tuberosum) | ||
| Hydrangea (Hydrangea spp.) | Plums (Prunus spp.) | Pods - Wisteria (Wisteria spp.) | ||
| Peas, sweet (Lathyrus odoratus) | ||||
| Tansy (Tanacetum vulgare) | ||||
According to the Sloan Kettering Cancer Center, raw or unripe elderberries contain toxic compounds and must be cooked sufficiently to avoid risk of cyanide toxicity.
| Plant Parts with Contact Toxicity | |||
| Any Part | Fruits | Seeds | Leaves |
| Anemone (Anemone patens) | Juniper (Juniperus communis,J. virginiana) | Castor beans (Ricinus communis) | Castor beans (Ricinus communis) |
| Buttercup (Ranunculus spp.) | Pasque flower (Anemone spp.) | Clematis (Clematis spp.) | |
| Daphne (Daphne spp.) | |||
| Milkweed (Asclepias spp.) | |||
| Poison ivy (Toxicodendron spp.) | |||
| Snow on the mountain (Euphorbia marginata) | |||
| Spurge (Euphorbia spp.) | |||
| Trumpet vine (Campsis radicans) | |||
Clematis (Clematis spp.) BY CHERYL MOORE-GOUGH
Burning Bush (Euonymus spp.) BY CHERYL MOORE-GOUGH
Iris (Iris spp.)BY CHERYL MOORE-GOUGH
Rhubarb (Rheum rhabarbarum) BY CHERYL MOORE-GOUGH
Morning Glory (Ipomoea spp.) BY CHERYL MOORE-GOUGH