Most of the plants grown in gardens do not present any hazard to humans or animals, and incidents of serious plant poisoning in the United Kingdom are rare.
Nevertheless, it is a responsibility of gardeners to see that no avoidable risks are presented, and knowledge of potentially harmful plants should be gained. It is an equal responsibility of garden users to be alert for their own safety and especially that of children and animals.
The Horticultural Trades Association (HTA) has worked with the Royal Horticultural Society (RHS) and other organisations to compile a list of potentially harmful plants and develop a Code of Recommended Retail Practice for labelling of plants at garden centres and nurseries. Look for safety information on labels when purchasing plants and learn what to do in the unlikely event of poisoning through eating or handling plants.
RISKS AND RESPONSIBILITIES
Fortunately, incidents of serious poisoning by plants are rare in the United Kingdom, and deaths very infrequent. These mostly involve adults who have either mistaken a poisonous plant for an edible one or misjudged the dose of a herbal remedy. The toxic constituents of some poisonous plants are invaluable medicinal drugs when administered at a low dosage under proper supervision.
However, they can be fatal if misused and it is important that possible risks are understood. It is also important that the subject is seen in proper perspective, to avoid unnecessary alarm and spoiling the enjoyment of gardens and gardening. It is reasonable to expect individuals always to exercise proper responsibility for their own safety and that of children and pets in their charge within the house and garden environment. At the same time gardeners should take care to prevent exposure to high risk.
WHERE’S THE HARM?
Many plants, or parts of them such as fruits and seeds, are safe and good to eat and are recognised as food plants.
Most others found in the garden as ornamental plants or weeds are not dangerous. Some may cause a digestive upset and discomfort if eaten, as will unripe fruit or raw rhubarb stalks, whilst a very few garden plants are more hazardous and could cause severe poisoning.
Many of the plants to be avoided are already well known to be potentially hazardous. Some have an unpleasant taste which reduces the likelihood of a dangerous quantity being eaten, whilst others just do not look edible. Nibbling plants is mainly a hazard of childhood, so small children may be vulnerable until they can be taught not to eat any part of a growing plant.
A sensible rule is: if it isn’t recognised food, don’t eat it. Make sure children know this. As well as the danger of poisoning through eating plants, there is also the possibility of suffering an irritant or allergic reaction through contact with a plant or its sap.
Gardeners are perhaps more at risk of these effects, for example while weeding or pruning. There are three main types of contact hazard:
1) Irritant sap may cause a burning sensation and sometimes blistering of the skin; anyone can be affected if the exposure is sufficient.
2) Some plants contain chemicals called allergens. These do not affect everyone, but some individuals may acquire a sensitivity to them resulting in an allergic reaction. This is often a form of dermatitis but may, in rare cases, be more far-reaching, as with nut allergies.
3) A very small number of plants have sap which renders the skin excessively sensitive to strong sunlight. Contact with a plant followed by exposure to sunlight results in very severe localised sunburn with blistering and a long-lasting skin discolouration. Farm animals are more likely to be exposed to the danger of poisoning than domestic animals, but puppies are notoriously adventurous. Never leave hedge clippings or uprooted plants in reach of pets or farm animals; in many cases the withered condition adds to the risk of poisoning. Most animals seem to be aware of and avoid growing plants that could harm them but parts of plants, or dead and shrivelled specimens, are often not recognised.
PURCHASE PLANTS WISELY
The HTA has issued a Code or Recommended Retail Practice relating to the labelling of potentially harmful plants.
This is based on research carried out by a project group consisting of the Medical Toxicology Unit, Guy’s and St Thomas’ Hospital Trust, the RHS and the Royal Botanic Gardens at Kew.
It is a voluntary Code produced to address public concern and sets out guidelines for keeping customers informed of potentially harmful plants at the point of purchase. This is part of a broader responsibility, shared by all concerned with the sale and display of plants, to provide good advice on the subject.
Many of the plants listed below can be viewed on our Plant Finder.
PLANTS TO RECOGNISE
Here is a list of plants which are often found in gardens, or available for sale. It describes three types of potential risk; skin irritants, eye irritants and poisons. The poisons category includes plants known to present any level of hazard. When eaten, some may cause mild illness, while very few may cause severe poisoning.
The correct approach is to avoid eating any plant listed as poisonous.
- Acalypha (Copperleaf): skin and eye irritant, poisonous
- Acokanthera (Bushman’s Poison): poisonous
- Aconitum (Monkshood): skin irritant, poisonous
- Actaea (Baneberry): skin irritant, poisonous
- Adenium (Desert Rose): poisonous
- Aesculus (Horse Chestnut): poisonous
- Aglanonema (Painted Drop Tongue): skin and eye irritant, poisonous
- Agrostemma (Corn Cockle): poisonous
- Allamanda: skin and eye irritant, poisonous
- Alocasia (Elephant’s Ear Plant): skin and eye irritant, poisonous
- Aloe: poisonous
- Alstroemeria (Peruvian Lily): skin irritant
- Amaryllis (Belladonna Lily): poisonous
- Anthurium (Flamingo Flower): skin and eye irritant, poisonous
- Apocynum (Dogbane): harmful if eaten
- Arisaema (Cobra Plant): skin and eye irritant, poisonous
- Arum (Lords and Ladies): skin and eye irritant, poisonous
- Asparagus (Asparagus Fern): may cause skin allergy,
- fruits poisonous
- Atropa (Deadly Nightshade): skin irritant, poisonous
- Brugmansia (Angel’s Trumpet): poisonous
- Brunfelsia (Yesterday, Today and Tomorrow): poisonous
- Caladium (Angel Wings): poisonous
- Calla palustris (Bog Arum): skin and eye irritant, poisonous
- Capsicum (Chilli Pepper): skin and eye irritant, poisonous
- Chelidonium majus (Greater Celandine): skin and eye irritant, poisonous
- Chrysanthemum: skin irritant
- Colchicum (Autumn Crocus): poisonous
- Colocasia esculenta (Taro): poisonous, skin and eye irritant
- Convallaria majalis (Lily of the valley): poisonous
- Coriaria: poisonous
- Cupressocyparis leylandii (Leyland Cypress): skin irritant
- Daphne: skin irritant, poisonous
- Datura (Jimsonweed, Stinkweed): poisonous
- Delphinium (Larkspur): poisonous
- Dictamnus (Burning Bush): skin irritant
- Dieffenbachia (Dumbcane): skin and eye irritant, poisonous
- Digitalis (Foxglove): poisonous
- Dranunculus (Dragon Arum): skin and eye irritant, poisonous
- Echium: skin irritant
- Epipremnum (Devil’s Ivy): skin and eye irritant, poisonous
- Euonymus (Spindle Tree): poisonous
- Euphorbia (Spurge): skin and eye irritant, poisonous. N.B. Poinsettia, E. pulcherrima, is not harmful
- Ficus benjamina (Weeping Fig): may irritate skin
- Ficus carica (Fig): skin and eye irritant
- Fremontodendron: skin and eye irritant
- Gaultheria (Pernettya): poisonous
- Gelsemium (False Jasmine): poisonous
- Gloriosa superba (Glory Lily): poisonous
- Hedera (Ivy): skin irritant, poisonous
- Helleborus (Christmas Rose, Lenten Rose): skin irritant, poisonous
- Heracleum mantogazzianum (Giant Hogweed): severe skin irritant in bright sunlight
- Hippeastrum: poisonous
- Homeria: poisonous
- Hyacinthoides (Bluebell): poisonous
- Hyacinthus (Hyacinth): skin irritant
- Hyoscyamus (Henbane): poisonous
- Hypericum perforatum (Perforate St. John’s wort): poisonous
- Ipomoea (Morning Glory): poisonous
- Iris: skin irritant, poisonous
- Kalmia (Calico Bush): poisonous
- Laburnocytisus adamii: poisonous
- Laburnum: poisonous
- Lagenaria (Bottle Guard): poisonous
- Lantana: poisonous, skin irritant
- Lobelia (except bedding lobelia): somewhat poisonous, skin and eye irritant
- Lupinus (Lupin): somewhat poisonous
- Lysichiton (Skunk Cabbage): poisonous, skin and eye irritant
- Mandragora (Mandrake): poisonous
- Mirabilis (Marvel of Peru, Four o’clock flower): skin irritant, poisonous
- Monstera deliciosa (Swiss Cheese Plant): skin and eye irritant, poisonous
- Narcissus (Daffodil): skin irritant, poisonous
- Nerium (Oleander): poisonous
- Nicotiana (Tobacco Plant): poisonous
- Oenanthe crocata, O. aquatica, O. phellandrium (Hemlock Water-dropwort, Water-dropwort): poisonous
- Opuntia microdasys (Bunny Ears Cactus): skin irritant
- Ornithogalum (Star-of-Bethlehem): skin irritant, poisonous
- Papaver somniferum (Opium Poppy): poisonous
- Passiflora caerulea (Passion Flower): poisonous
- Pedilanthus: skin and eye irritant, poisonous
- Philodendron: skin and eye irritant, poisonous
- Phytolacca (Pokeweed): skin irritant, poisonous
- Podophyllum (May Apple): poisonous
- Polygonatum (Solomon’s Seal): poisonous
- Polyscias: skin irritant, poisonous
- Primula obconica: skin irritant
- Prunus laurocerasus (Cherry Laurel): poisonous
- Prunus lusitanica (Portuguese Laurel): seed kernels are poisonous
- Rhamnus (Buckthorn): skin irritant, poisonous
- Rhaphidophora: poisonous, skin and eye irritant
- Rhus verniciflua, R. radicans, R. succedanea, R. diversiloba, R. rydbergii, R.striata, R. toxicarium, R. vernix (Japanese Lacquer Tree, Poison Ivy, Sumach): poisonous, severe skin irritant
- Ricinus communis (Castor Oil Plant): poisonous
- Robinia pseudoacacia (Locust Tree): poisonous
- Ruta (Rue): severe skin irritant in bright sunlight
- Scopolia: poisonous
- Solandra (Chalice Vine): poisonous
- Solanum: poisonous
- Solanum pseudocapsicum (Christmas Cherry, Winter cherry): poisonous
- Spartium junceum (Spanish Broom): poisonous
- Spathiphyllum (Peace Lily): poisonous, skin and eye irritant
- Sophora (Pagoda Tree): poisonous
- Symphoricarpos (Snowberry): poisonous
- Symphytum (Comfrey, Russian Comfrey): poisonous
- Syngonium (Goosefoot Vine): skin and eye irritant, poisonous
- Tabernaemontana (Crepe Jasmine): poisonous
- Taxus (Yew): poisonous
- Thevetia (Yellow Oleander): poisonous, skin irritant
- Tulipa (Tulip): skin irritant
- Veratrum (False Hellebore): poisonous
- Vitex (Chaste Tree): skin irritant
- Wisteria: poisonous
- Xanthosoma: poisonous, skin irritant
- Zantedeschia (Arum Lily): skin and eye irritant, poisonous
- Zigadenus (Death Camas): poisonous
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