We are lucky here in the UK that our natural environment is relatively safe when compared to that of other countries. That said, there are still dangers in our gardens. In this article, we will discuss some of the poisonous flowers that grow in the UK. Understanding which flowers and other plants are poisonous can help gardeners to keep themselves and their families and pets safe.
The list in this article is by no means a comprehensive one – but many of the most common poisonous flowers are included. Care should always be taken around these plants. Though it is worthwhile bearing in mind that you should always be careful around plants that you do not know or cannot be 100% sure of identifying correctly.
Poisonous Flowers That Could Kill
These poisonous flowers all contain serious poisons, that could severely harm or even kill the unwary, though some are attractive ornamentals and great for wildlife, and so could still find a place in your garden:
Foxglove (Digitalis purpurea)
The entire plant can be deadly, especially the leaves high up on the stem. While digitalin, digitoxin and digitonin are used medicinally, ingesting the plant can cause extreme heart problems and even death if left untreated.
Deadly Nightshade (Atropa belladonna)
Deadly nightshade is well known for its lethal properties. Both the foliage and the berries contain toxins such as atropine, scopolamine and hyoscyamine.
While most people are aware of Belladonna or Deadly nightshade as a poisonous plant, few realise that some common food plants are in the same plant family. Potato and tomato foliage, for example, should never be eaten.
Lords & Ladies/Cuckoo Pint (Arum maculatum)
The bright red and orange berries of this woodland and hedgerow flowering plant are poisonous. They can cause irritation to the throat and stomach, and swelling and pain that can lead to a difficulty in breathing.
Monkshood/ Wolfsbane (Aconitum napellus)
All parts of this plant are highly toxic and can be fatal if consumed. Aconite and aconitine are believed to be the key toxins. Ingestion can cause severe stomach upset but, more crucially, and dangerously, can affect the heart.
All parts of the rhododendron are poisonous to humans (and dogs) and any part, flowers or leaves, if ingested, can lead to coma and death in extreme cases.
Lily of the Valley
These pretty, sweet-smelling plants can cause severe problems with only a tiny bite and ingestion can, again, lead to coma and death in some instances.
This is another common garden plant that can be deadly. The poison is a cyanogenic glycoside which causes a drop in blood pressure and potentially convulsions and death.
These flowers may be beautiful to look at but they are definitely not for eating. The entire plant contains toxic alkaloids though the young leaves and mature seeds are the most dangerous.
Oleander (Nerium oleander)
Nerium oleander can be extremely dangerous as it can serious harm and even kill with just a single leaf. The whole plant is poisonous, including the nectar and sap.
Poisonous Flowers That Could Make You Very Sick
These following flowers are very unlikely to be deadly, but could make you very sick if they are accidentally ingested:
While daffodil bulbs are not the most deadly of poisons, it seems they account for many accidental poisonings each year, most of which occur when people mistake the bulbs for onions.
Bluebells are also poisonous and can also resemble spring onions, which is the reason why they are accidentally eaten. Like daffodil bulbs, eating them can cause severe digestive upset.
Other Poisonous Garden Plants:
Flowers are not the only plants in your garden that are poisonous. A number of trees and shrubs are also poisonous plants. These include (but, of course, are not limited to):
Hemlock (Conium maculatum)
Hemlock can cause vomiting, paralysis of the nervous system and death due to respiratory failure. It contains five alkaloids – coniine, conhydrine, pseudoconhydrine, methyl-coniine and ethyl-piperidine, which are responsible for its poisonous properties.
All parts of the yew tree except the outer flesh of the berries are poisonous and can cause death without interceding symptoms within a few hours.
Laburnum is another common garden tree that can cause poisoning. Poisoning from this common garden tree often occurs when kids mistake the unripe seed pods for peas or beans.
All parts of mistletoe are poisonous but especially the berries. Ingestion can cause severe digestive problems which have even led to death in humans and can also be particularly of concern for pets.
Black Bryony (Tamus communis)
This plant is common on the hedgerows and woodland edges of areas to the south of the UK. It has shiny and appealing scarlet berries that appear in clusters that twine together but those berries are highly toxic.
Spindle (Euonymous europaeus)
This tree or shrub is fairly easy to miss and may go unnoticed on the fringes of your garden until the fruits appear in the autumn. The fruits are bright pinkish-red and eventually burst open to reveal a bright orange seed. Be warned. These eye-catching fruits are also highly toxic.
Holly (Ilex aquifolium)
Holly is familiar to most people though few stop to think about the toxicity of the berries. Berries only form on the female tree. While eating a few berries is likely to give children a serious stomach upset, if they eat more than twenty it can be fatal.
Ivy (Hedera helix)
The berries of all different kinds of ivy should be avoided. While it is extremely uncommon for humans to eat enough of these berries to be poisoned, berries can cause severe reactions in the mouth, on the tongue, lips and on surrounding skin and are highly toxic.
Tutsan (Hypericum androsaemum)
This shrub-like plant likes to grow in damp hedgerows and in woodland. It is in the St. John’s Wort family and though it is of use in herbal medicine, the berries are toxic and should most definitely not be consumed as a food stuff.
Poisonous Plants Containing Saponins
Many of the other plants often listed as poisonous that can be grown in UK gardens have poisonous saponins. Though they are poisonous, saponins are poorly absorbed by human body. This means that they mostly pass through without harm.
Interestingly, saponins are found in a range of common plants – including a range of plants that we usually eat, such as some beans, and some leafy greens. Cooking, and discarding cooking water,will normally remove most of these poisonous saponins. That said, it is not advisable to eat large quantities of food that contains saponins.
Saponins can be more dangerous for those with kidney or liver disease, and should be avoided by those who are taking warfarin, as they can interfere with anticoagulant therapy. So while beans and other plants with saponins are generally not poisonous, the fact that they contain saponins can make them a little dangerous for some.
However, saponins, while classified as a ‘poison’ can actually be beneficial for the health in smaller quantities. Clinical studies have suggested that including some saponins in the diet can promote good health. They act on the immune system in such a way that they protect the human body against certain cancers and can lower cholesterol levels, blood lipids and glucose response.
Plants Poisonous for Pets
Another thing to think about when planning a garden and considering which plants are poisonous is whether or not the plants you choose will be safe for pets. Some plants that are perfectly safe for humans are poisonous for dogs or cats. In addition to many of the plants on the list above, pets can also be harmed by plants that we would consider to be harmless. For example, alliums such as onions and garlic. All parts of these edibles are poisonous to dogs and cats.
Other flowers and plants that are poisonous for pets include:
- Morning Glory
- Rhubarb leaves
- Sweet pea
- Tulip bulbs
Again, this is,of course, an incomplete list.
Many plants can be poisonous in sufficient quantity, either for people, for pets, or for both. Accurate identification of plants in your garden, can taking care over which plants you choose to grow, is important for remaining safe in your garden.
Please share your own knowledge of poisonous flowers and other poisonous garden plants in the comments below.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.