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Poisonous Plants

Several people have asked me if I could compile a list of toxic plants, so here it is.

This list is not definitive – not by a long way - as there are thousands of them, but it does show most of the common plants that we use in our gardens that are, at the least, irritant and some are deadly.

I know that many of you do not realise that so many of these often-used plants are so dangerous.

Knowledge is definitely power in this case!


Aconitum, Aconite, monkshood, wolfsbane. All parts cause paralysis and heart palpitations.             


Agave americana, Century plant. Sap is extremely irritant


Azalea/rhododendron. Toxic in all parts. Very dangerous to grazing animals and honey made from the pollen can induce hallucinogenic symptoms in humans


Brugmansia suaveolens, Angels trumpets. Narcotic and hallucinogenic effect in all parts. Can be fatal to humans and animals.


Cerastogima plumbaginoide, Blue leadwort. Foliage can cause contact dermatitis


Cestrum nocturnum, Lady of the night. Poisonous fruits and smoke from cuttings is mildly toxic.


Convallaria majalis, Lily of the valley. Poisonous in all parts, especially berries.


Cytissus scoparius, English broom. Toxic in all parts, can cause heart palpitations.


Datura stramonium, Jimson weed, thorn apple, devil’s apple. All parts & particularly the roots and seeds are poisonous with hallucinogenic properties.


Delphinium, Larkspur. Foliage can cause discomfort and illness if ingested. Can kill cattle.


Digitalis, Foxglove, dead man’s bells. All parts are toxic causing heart and cerebral disturbances. The toxicity is concentrated in the growing tip.


Duranta, Skyflower. To humans, and especially children, the berries are deadly but birds can eat them without harm.


Echium, Bugloss. Irritant hairs causing rashes and can cause liver failure in grazing animals.


Euonymus europaeus, Spindle. All parts, especially the fruits, are poisonous.


Euphorbia, Spurge. All members of the family are toxic causing acute contact allergy. The sap in contact with the eyes can cause blindness. Pollen may cause respiratory allergy. Goats are immune to the toxin but pass it to humans through their milk.           


Ficus, Fig. Irritant sap and unripe fruits are poisonous (in f. carica).


Gelsemium sempervirens, Yellow jasmine. Entire plant is toxic; even bees are poisoned by its pollen.       


Grevillea, Silky oak, spiderflower etc. Entire family contains cyanide.


Hedera helix, Ivy. Entire plant causes skin irritation. Pollen causes respiratory problems. Ingestion provokes vomiting, convulsions and coma.          

                                                                                                                                                                 Heliotropium arborescens, Hot cherry pie. Ingesting the leaves can cause liver failure, especially in cats and dogs.


Ipomoea, Morning glory. Seeds are poisonous provoking hallucinogenic effects.


Lagunaria patersoniiNorfolk Island hibiscusSeed cases have very irritant hairs which inflame the skin for many days.


Lantana camara, Spanish flag. Foliage causes skin irritation and all parts are poisonous. Berries are toxic.


Ligustrum, Privet. Berries and leaves are poisonous and  can be fatal. Horses are  vulnerable. Pollen is high in allergens.   


Lupinus, Lupin. Poisonous in all parts, seeds are toxic.


Magnifera indica, Mango. The sap and peel can cause skin rashes.


Nerium oleander, Oleander. Extremely toxic in all parts – even honey from the pollen. Smoke from cuttings is poisonous & flowers falling into water deposits can poison it. Sap causes death.


Nicotiana family, Tobacco plant. All parts are poisonous, provoking addiction.


Phytolacca, Pokeweed. Sap can induce allergic reactions ranging from itching to death.


Plumbago, Leadwort. Foliage can cause skin irritation.


Primula obonica, German primrose. Foliage can cause skin irritation.


Ricinus communis, Castor oil plant. The seeds are very pretty but extremely toxic causing death if ingested.


Robinia family, Locust tree. Seeds are poisonous.


Sanguinaria canadensis, Bloodroot, greater celandine. Foliage can produce skin sores.


Silybum marianum, Milk thistle. Entire plant is harmful to humans and animals, especially cows and sheep.


Solandra maxima, Cup of gold vine. Pollen causes allergic problems.


Solanum family, Potatoes, tomatoes, deadly night-shade, potato vine, blue potato bush etc. Fruits are extremely toxic - in potatoes and tomatoes when green.


Taxus baccata, Yew. Poisonous in all parts, except the flesh of the fruit, but the seed is extremely toxic.


Thevetia Peruviana, Yellow oleander. All parts are very poisonous.


Wisteria sinensis, Chinese wisteria. Bark and roots are poisonous; ingestion of seeds can be fatal.


Zantedeschia, Calla lily. Leaves are toxic causing burning especially to the eyes and mouth.


Many bulbs are also poisonous; take special care with narcissus, hyacinth, lilies, autumn crocus and ranunculus. Members of the onion and garlic family, if ingested in large quantities, can be poisonous to cats and dogs.


My intention in highlighting these dangerous plants is not to scare you off using them. Some you may choose to avoid but most can make huge contributions to our gardens. Remember that many of them play important roles in the medical world. If you have children, educate them. It’s all very well banning these plants from your own garden but children are going to encounter oleander, for instance, growing everywhere, even wild in the campo. My grand-daughter spends a lot of time at the garden centre which is inhabited by many ‘nasties’ and, from very young, she was taught never to eat any plant without specific permission, to take care touching some and, when in doubt, always leave alone. She now gives these lessons to all her friends that visit!  And whilst she knows the ones to leave alone, she also knows the ones that are delightful to stroke; she knows to leave lantana berries alone but that the mulberries on the tree are delicious. She finds the ‘Wicked Ways of Plants’ totally fascinating and her memory is far sharper than mine, so she won’t forget!


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