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How much harm do plants actually cause?

Accidental Plant Poisoning

It cannot be said often enough that the number of serious incidents of accidental plant poisoning is extremely small but finding evidence to justify that statement is made more difficult because, in an odd way, the truth of it makes evidence hard to provide.

Because it is such a small problem, there is no point in expending resources to monitor it in any detail. Unlike, say, motor vehicle accidents or tourism numbers, there are no annual reports into plant poisoning.

But, there is one detailed study that, though now over twenty years old, offers an indication of the plants that do cause the very few incidents that occur.

The Experience of One Country

Evidence of the limited harm caused by plants comes from a 1996 paper  by Jaspersen-Schib et al and published by the Swiss Journal of Medicine entitled ‘Serious plant poisonings in Switzerland 1966-1994. Case analysis from the Swiss Toxicology Information Center’ (STIC)  

The researchers looked at 24,950 cases of contact with or ingestion of toxic plant material reported to the STIC. Severe plant poisonings occurred in only 152 cases (0.6% of the total) and sufficient details were available for 135 cases to be analysed. These cases involved 112 adults and 23 children and included 5 adult deaths.  

[It would be wrong to assume that a country as small as Switzerland and with its particular geography could be typical of the whole world but it does seem to be broadly similar to the USA where, in 2008, of 63,362 'reported poisonings' only 67 (0.1% of the total) produced a ‘major’ outcome with a further 1,252 (2.0%) having ‘moderate’ effects. The 63,362 number is calls to US Poison Control Centres and many of these may have been simply seeking information. This doesn't stop some people claiming that this is the number of actual poisonings and labelling these plants as 'wicked' as a result.]

In terms of number of cases, within the 135, there were eleven plants resulting in more than one case. These were;  

• Atropa belladonna, deadly nightshade, (42 cases)
• Heracleum mantegazzianum, giant hogweed, (18)
• Datura stramonium, jimsonweed, (17)
• Dieffenbachia, dumb cane, (11)
• Colchicum autumnale, naked ladies,(10 including 2 deaths)
• Veratrum album, sneezewort, (8)
• Aconitum napellus, monkshood, (4)
• Aesculus hippocastanum, horse chestnut, (3)
• Hyoscyamus niger, black henbane, (3)
• Oenanthe crocata, hemlock water dropwort, (2 including 1 death)
• Taxus baccata, yew, (2 including 1 death)  

The fifth fatal case was the result of the only reported incident of poisoning by Narcissus pseudonarcissus. This is the only case of fatal daffodil poisoning I have heard of and it resulted from inhalation of plant material which would, of course, have avoided the gastrointestinal upset that is usually found with daffodil ingestion and usually limits the effects of the toxins.  

Other plants involved in a single serious poisoning during the 29 years studied were Arum maculatum (cuckoopint), Asarum europaeum (wild ginger), Chrysanthemum vulgare (common tansy), Cyclamen persicum (cyclamen), Datura sauveolens (angels’ trumpet), Glycyrrhiza glabra (liquorice), Laburnum anagyroides (laburnum), Lycopodium (clubmoss), Nerium oleander (oleander), Senecio vulgaris (groundsel) and Vicia faba (broad bean).  

That the most common (albeit extremely rare) cause of serious poisoning, deadly nightshade, did not result in any fatalities suggests that its danger if often over-stated. That giant hogweed ranks second as a cause of serious harm is an answer to those who say that concern about Heracleum mantegazzianum is overblown and that there are many more dangerous plants around.


The POISON GARDEN website is not connected with Alnwick Garden Enterprises Ltd and/or The Alnwick Garden Trust.







A to Z Links

Introduction to the A to Z section
Abrus precatorius, rosary pea
Aconitum lycoctonum, wolfsbane
Aconitum napellus, monkshood
Actaea racemosa, black cohosh
Actaea spicata, baneberry
Aesculus hippocastanum, horse chestnut
Amanita muscaria, fly agaric
Aquilegia atrata, columbine
Aristolochia clematitis, birthwort
Artemisia absinthium, wormwood
Arum italicum, Italian cuckoopint
Arum maculatum, cuckoopint
Aspergillus fumigatus
Atropa belladonna, deadly nightshade
Brugmansia suaveolens, angel's trumpet
Bryonia dioica, bryony
Buxus sempervirens, common box
Camellia sinensis, tea
Cannabis sativa, marijuana
Catha edulis, khat
Chelidonium majus, greater celandine
Cimicifuga racemosa, black cohosh
Claviceps purpurea, ergot
Clematis vitalba, old man's beard
Colchicum autumnale, naked ladies
Conium maculatum, poison hemlock
Convallaria majalis, lily of the valley
Cynoglossum officinale, hound’s tongue
Daphne mezereon, spurge olive
Datura stramonium, thorn apple, jimsonweed
Datura suaveolens, angel's trumpet
Delphinium, larkspur
Digitalis spp., foxglove
Dracunculus vulgaris, dragon arum
Echium vulgare, viper’s bugloss
Eranthis hyemalis, winter aconite
Erythroxylum coca, cocaine
Euonymus europaeus, spindle tree
Euphorbia x martinii, red spurge
Euphorbia pulcherrima, poinsettia
Fritillaria spp., fritillary
Galanthus nivalis, snowdrop
Hedera helix, common ivy
Helleborus spp., hellebore
Heracleum mantegazzianum, giant hogweed
Hyacinthoides non-scripta, bluebell
Hyoscyamus niger, black henbane
Ilex aquifolium, holly
Jacobaea vulgaris, ragwort
Juniperus communis, common juniper
Laburnum anagyroides, laburnum
Lactuca serriola, prickly lettuce
Leucojum aestivum, snowflake
Lithospermum officinale, gromwell
Lolium temulentum, darnel
Malus 'John Downie', crab apple
Mandragora officinarum, mandrake
Mercurialis perennis, dog’s mercury
Narcissus, daffodil
Nepeta faassenii, catmint
Nerium oleander, oleander
Nicotiana sylvestris, tobacco
Oenanthe crocata, hemlock water dropwort
Papaver somniferum, opium poppy
Pastinaca sativa, parsnip
Polygonatum odoratum, angular Solomon's seal
Prunus laurocerasus, cherry laurel
Pulsatilla vulgaris, pasque flower
Ranunculus acris, meadow buttercup
Rheum x hybridum, rhubarb
Rhododendron spp.
Rhus radicans, poison ivy
Ricinus communis, castor oil plant
Rosmarinus officinalis, rosemary
Rumex obtusifolius, broad-leaved dock
Ruta graveolens, rue
Salix alba, white willow
Salvia divinorum, sage
Scutellaria laterifolia, Virginian skullcap
Senecio jacobaea, ragwort
Solanum dulcamara, woody nightshade
Solanum melongena, aubergine
Strychnos nux-vomica, poison nut
Symphoricarpos albus, snowberry
Symphytum spp., comfrey
Taxus baccata, yew
Toxicodendron radicans, poison ivy
Thevetia peruviana, yellow oleander
Urtica dioica, stinging nettle
Veratrum album, white hellebore
Verbascum olympicum, Greek mullein
Vinca major, greater periwinkle
Viscum album, mistletoe
Vitex agnus-castus, chaste tree