Poisonous Plants: 17 Toxic Plants In Your Garden - Fantastic Gardeners (2024)

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The abundance of beautiful and well-grown houseplants gives a special sense of comfort at home. Apart from being pleasing to the eye, some house plants have the ability to purify the air quality.

However, if you turn your home into a full-size botanical garden, you might do yourself bad favour, as some common house and garden plants also happen to be toxic. They can carry not only health risks but also life-threatening hazards, especially if you are not careful with handling them properly.

Hydrangea

Symptoms: vomiting, heavy breathing, lethargy, stomach ache and coma in the worst cases.

Hydrangea hortensis is a medium-sized bush with gorgeous blossoms. It's a perennial decorative plant which blooms every year from spring until autumn with large, ball-shaped flowers that reach 30cm in diameter. Hydrangea's petals are long-lasting and, most often, come in pink, whereas some sorts are white, red and blue-coloured. Depending on the pH contents of the soil, the colour of the hortensis changes from blue (low pH), through pale (neutral pH), to purple (high pH).

In the past, hydrangeas were swamp plants and that's their most significant peculiarity. In Europe, hortensias came at the end of the 19th century from China and Japan. With years, many more hybrid sorts were imported. Today, there are over 30 different species, and around 12 of them are popular garden breeds.

Unfortunately, all parts of the plant contain cyanide, one of the deadliest poisons known to man. On the positive side, they contain low amounts of it. Hydrangeas are moderately toxic for pets if ingested, same is the deal with children. Grown-up humans can show more resilience.

Nevertheless, should poisoning occur, it comes with vomiting, heavy breathing, lethargy, stomach ache and, in worst cases, coma.

Water Hemlock

Symptoms: fatal outcome with violent and painful seizures.

Water hemlock is one of the most toxic plants in nature. Infamously, Socrates' sentence to death was executed by him ingesting hemlock. It's not a decorative plant you will sow in your garden, but it's a widespread weed. It can easily be confused with a blooming carrot, as it looks and smells harmless enough. If you do spot it in your garden, pull it up using gloves.

Water hemlock has little white buds – altogether they resemble an umbrella. The plant can reach around a metre in height and belongs to the carrot family. The stalk of the plant is full of multiple small tubular hollows that are filled with highly toxic brownish liquid.

Even a small amount of its toxic ingredient can poison livestock or humans. Cicutoxin is a palatable cause of convulsions and attacks the central nervous system directly. Severe poisoning on the plant can lead to seizures and, subsequently, death. Seek immediate medical assistance if you or your child ingests the plant.

For cattle, the roots are more dangerous, especially if exposed after ploughing. Examine your garden for the weed and deal with its infestation immediately, as smaller pets don't stand a chance against its toxicity.

Oleander

Symptoms: severe digestive problems and even death.

Nerium oleanders are species of evergreen perennial bushes and trees from Apocynaceae family. There are three types that exist in nature – they grow in the Mediterranean, as well as in the subtropical regions of Asia.

Despite its toxicity, the plant is highly valued as a decorative flower, with beautiful red, white, yellow and pink fragrant blossoms. Its chemical substances are widely used in medicine to heal heart disease. It's also spread around the world as a decoration for gardens and parks because the flower is very easy to maintain. But it's deadly toxic.

Symptoms include drowsiness, vomiting, slowed heart rate, arrhythmias, seizures and tremors. In one recorded case a child suffered effects from a single leaf, whereas the same amount is enough to kill a dog.

What's more, if you burn oleander, the smoke will be toxic for you, so refrain yourself from doing so.

Daffodil

Symptoms: nausea, vomiting, diarrhoea.

Daffodil belongs to the Amaryllidaceae family. It comprises of 60 varieties, originating from the moderate climate regions of Central and Western Europe, West Asia and North Africa. Many sorts are highly valued as decorative flowers. The hybrid cultivated types are over 12 000.

Daffodils are one of the first plants that blossom in your garden without fear of the late spring frost.

However, if the bouquet of daffodils stays for too long in a room, people start getting headaches. In fact, different parts of the plant are mildly poisonous. Unlike other toxic domesticated flowers, daffodil poisoning doesn't lead to a fatal end, even in pets, but the reactions are unpleasant. Symptoms include vomiting, dehydration, drooling and stomach ache. In some cases, tremors, convulsions and heart irregularities can be observed, especially in pets.

We know you wouldn’t put them on your dinner plate, but don’t let your dog root around in garden beds where you grow daffodils.

Foxglove

Symptoms: irregular pulse and heartbeat, upset stomach and mental confusion. May be fatal.

Foxglove (also known as digitalis) is a cold- and dry-resistant plant. It is a popular decorative plant due to its beautiful blossoms. Digitalis is widely used in medicine for drugs that power up your cardiac system. Indeed, if used correctly, the plant is a life-saver. Unfortunately, the wild and the cultivated flowers are both deadly poisonous if ingested directly. This is one of the reasons NOT to prepare your own homemade heart remedies with the plant, as the dose that you might get out of it will be completely unregulated.

Watch out for your children when they play outdoors – a handful of its trumpet-like blossoms are enough to poison them, let alone your pets. Clinical symptoms include increased heart rate, nausea, vomiting, seizures. Antidotes may be needed in potential life-threatening cases, to deal with the toxin.

Elephant ear

Symptoms: irritation and feelings of intense burning. If tongue swells enough it can block the passage of air, thus leading to death.

Caladium (a.k.a. Elephant ear) is a beauteous plant with intricate leaf colours. Its basic shades are red, pink, white and green. You can stumble upon different colour and pattern combinations across the flower stores. The birthplace of caladium are the tropical forests of South America. It's a grass plant with decorative sharp, heart-shaped leaves. Caladium never reaches more than 30 cm in height. Normally, the leaves have green edges, whereas the middle's where the extra colour appears.

Elephant ear contains calcium oxalate crystals, which causes injury when chewed. Symptoms are vomiting, drooling, swelling tongue and oral cavity as a whole, which can lead to breathing difficulties.

The poison is not life-threatening, but should symptoms occur, seek a veterinarian’s help if your pet’s been privy or a physician if your kid has ingested the plant.

Poison Ivy

Symptoms: nasty rashes, itches, blisters and hives on the skin.

Poison ivy is a perennial plant that reaches around 30 cm in height if it stays on the ground. However, it is a vine plant, which means it climbs on trees, houses and walls, and can get as long as 100 ft. Even though its name sounds dangerous, it is generally only slightly poisonous. If pets come in contact with the plant (through touch or ingestion), irritation and rashes are observed. Thankfully for our little furry companions, their thick hair serves as a protection from poison ivy and its toxic oils stay clear of their skin.

Unfortunately, when it comes to humans, we need to be extra careful with the itchy plant. If you are travelling through wild places, make sure to have protective clothes covering your skin.

Philodendron

Symptoms: intense salivation, mouth burning and tongue swelling.

Philodendron (Monstera Deliciosa), originates from the warm tropical forests of South America. It's an evergreen plant, which is sometimes called a “green tree” (philodendron) or just a “weeping tree”, since when the air humidity increases, large water drops form on the leaf edges and drip down. In its natural habitat, the Monstera is a strong vine plant with swift green stems that look like snakes.

Its poisonous contents have undergone as many researches as the results received from them. Humans are highly resistant to the levels of oxalate in the plant, and a fatal end is highly unlikely. Digesting parts of the plant can lead to salivation, mouth burning and tongue swelling in some cases. As far as pets are concerned, science cannot say with an absolute certainty whether philodendron leads to fatal poisonings. In any case, be protective of your pets and don't let them eat the plant, just to be on the safe side.

Lily of the Valley

Symptoms: irregular heartbeat and pulse, mental confusion and upset stomach.

This plant's toxic effects are as strong as its medicinal ones. It blooms in early spring with beautiful little white bell-shaped petals, for which there's a legend. It's considered that this plant appeared after Jesus was crucified and, from the tears of Maria Magdalena, the flower grew. A completely different myth suggests that here in Britain, the lily-of-the-valley grows in the forest, where the hero Leonard defeated an enormous dragon. The hero's blood drops that fell on the ground, turned into the flowers whose bells rang to celebrate his win.

The lily-of-the-valley can easily induce fatigue, diarrhoea and vomiting. Extreme poisoning after ingestion of the plant leads to irregular heart beat and mental confusion. Always wash your hands well after touching the plant – better yet, use gloves. Even a small dosage is enough to lead in a fatal end in pets and children.

Dumb Cane

Symptoms: intense burning and irritation, tongue swelling.

There are over 50 different sorts of dumb canes (or dieffenbachia) growing around the world. They differ by their leaf form and colouration, overall size and other specific biological factors. Usually, its leaves are a motley combination of dark green, light green, white and yellow.

You can see dieffenbachia in almost every home or institution. People prefer it as a foliage plant namely because of its patterned leaves. It can reach up to two metres in height.

Dumb canes are indeed toxic, but not as dangerous as to threaten a human's or pet's life in general. However, the name doesn't come in vain – some severe cases of swelling after ingesting the plant lead to losing the ability to talk. In any case, overdosage of calcium oxalate leads to intense pain and burning sensation, that won't go away for at least half a day. Be careful not to touch the sap of the plant and if you happen to do it, wash your hands before reaching for your face or eyes.

Ficus

Symptoms: rashes, itching and stomach ache.

Ficus is a preferred decorative plant, mainly because of its beautiful and thick, tree-like crown, which you can easily form with a bit of care and perseverance. In warmer climates, the ficus can easily thrive on the outside, too. The birthplace of the pretty boy is South-East Asia and Australia.

All of the ficus plants are evergreen trees or bushes, with small, shiny leaves which can be either plain green or dark green, motley (different combinations of green, dark green, white and even grey), smooth or curly – with pointy ends. Domesticated house plants can reach up to 3-4 metres, whereas in nature, the ficus tree can grow higher than 20 m.

The Ficus family consists of almost 800 different species of shrubs and trees – also called rubber plants. They easily thrive at home environment and that poses a danger for children and pets, since the plant is toxic. Yet, it's not as severe as other poisonous plants. Children can get an itching or rash when they touch the sap, whereas pets might have a worse reaction and have stomach aches and diarrhoea.

Desert Rose

Symptoms: malaise, dizziness, vomiting and nausea.

Desert rose, also known as adenium, is an extremely interesting plant with a peculiar shape. The representatives of its family belong to the tree-like succulents. The cultivated ones are quite picky when it comes to living conditions. Not only that, but they also happen to contain one of the deadliest poisons known to man.

It is said that African tribes dip their arrows before a hunt in the extracted toxic sap of the flower – a single arrow can kill an elephant after several hours. The toxin here is ouabain – a cardiac glycoside, which causes vomiting, diarrhoea, mouth and throat blisters, drooling and intestinal pain.

The good news – it's fairly difficult for your body to extract on its own the poison particles of the sap. In any case, protect your pets and your children from coming in close contact with this deadly flower.

Belladonna

Symptoms: intensive digestive disturbance and death.

Belladonna is a perennial shrub from the Solanaceae family. Out in the wild, it grows in Europe, Northern Africa and Western Asia. It's also naturalised in different regions of North America. In native climate regions, it can last several years. The tallest height it can reach as a mature plant is about a metre.

Belladonna is one of the deadliest plants on Earth. A small chewed leaf is enough to kill an adult, let alone little children and pets.

Its flowers are as beautiful as the plant is toxic, therefore it's often grown as a decorative shrub. It also doesn't require a lot of maintenance and is a fitting plant for newbie gardeners.

Belladonna is named after the oldest of the three Ancient Greek goddesses of destiny – the moiras. Atropa is the one that is responsible for cutting the final thread of a human's life – which brings death.

Apart from dilating pupils and dry mouth, with Belladonna poison come hallucinations, very loud heart beats which even people standing close to you can hear, convulsions and coma. These symptoms can occur hours after ingesting the plant or even a few days later on, which means you have to be extremely cautious with the plant.

Rhododendron

Symptoms: vomiting, nausea, difficult breathing, prostration and coma.

Rhododendron belongs to the same family as blueberries and azalea. It's grown in thousands of different shapes and reaches up to 5 metres in height. There are both evergreen and deciduous sorts – all of them having oval leathery leaves. They bloom in April and May for around 3-4 weeks in different colours – red, violet, white, pink, yellow and blue, as well as in different combinations of those.

All those factors make them a great addition to your garden, but be warned – the honey extracted from rhododendrons is referred to as “mad honey.” In ancient times, Roman troops were given honey made of rhododendrons and the unsuspecting soldiers got poisoned. Vomiting, confusion, and cardiac problems are some of the severe side effects of grayanotoxin – the toxin contained in all parts of the plant, particularly the nectar.

And, even though in a raw condition you have to eat hundreds of flowers to get poisoned, as little as 0.2% per body weight for a smaller animal, such as a cat or a dog, is enough to result in bad poisoning.

Aloe

Symptoms: tremors, depression, stomach disorders.

Aloe is a succulent plant species, which includes around 180 varieties in its family, which are native to South Africa. Aloe is widely used in medicine and in textile industry. Several types are decorative and are grown in home. Its leaves are thick and juicy – a bitter gel is extracted from it. The juice has an antibacterial effect and soothes burned skin.

A thin layer of Aloin, a yellowish toxic substance, however, covers the gel and it's highly toxic. Ingestion of large quantities leads to stomach disorders, anorexia and depression. Tremors are seen in rare cases.

Angel's trumpet

Symptoms: fast heartbeat, difficult breathing, nervousness, hallucinations, loss of memory, coma, paralysis, coma and death.

The angel's trumpet (also known as brugmansia) is an easy to grow shrub that adores tropical and subtropical climate with cool nights and warm days. It originates from South America and has flavourful, heavy flowers which resemble trumpets. They reach up to 20cm in length and bloom in different colours – white, yellow, pink, orange and creamy. Its leaves are large, dark green and shiny. The plant is quite tall – it reaches at least 1.80m in height and can grow up to 6m.

However, it's also a member of the nightshade family, where, despite having tomatoes and potatoes, which have edible non-poisonous parts, all parts of brugmansia are toxic. The plant contains highly toxic and potentially deadly alkaloids such as scopolamine, hyoscyamine and atropine, but not only. The highest concentration of these toxins is found in its seeds and leaves.

A very unfortunate case of a young 18 old man intentionally ingestingburgmansia tea has been reported. The boy performed self-amputation with pruningshears under the influence of the plant. Reportedly the dosage boiled was just two flowers of Angel's Trumpet.

The patient confirmed a complete amnesia during the amputation. If you are going to handle the plant, it's recommended to use gloves, because one of the easiest ways for the poison to penetrate your body is through touching your eyes or food with contaminated hands. It has been used as a hallucinogen, yet, high dosages can lead to severe poisoning with a fatal outcome.

Monkshood

Symptoms: burning, tingling, numbness, gastrointestinal problems and subsequent death.

Aconitum, also known as Wolfsbane, is a highly poisonous plant. It's scientific name Aconitum probably originates from the Akonitos mountain in Anatolia. There, according to Greek mythology, Hercules led the three-headed dog Cerberus out of the underworld kingdom of Hades. The dog's saliva gives birth to Wolfsbane.

The aconite leaves are deeply pierced. Its flowers grow at around a metre of height. It blooms during July and August.

The plant is one of the most poisonous in the world and is sometimes used in phytotherapy due to its low therapeutic index. It has soothing and hom*oeopathic action.

Every part of the wolf's bane will kill you. Even if you touch the plant with bare hands and then you touch your face or food, you may have to be taken to a hospital. It was used by hunters to dip arrows in poison and hunt game.

In the past, the flower was used as a tool to find werewolves. When the flower was close to the chest of the suspect and a yellowish shadow thrown from the plant appeared, the person was considered, in fact, a werewolf.

The beauty of the flower comes with a heavy price. All gardeners are advised to proceed with extreme caution.

What to do if you suspect a poisoning?

No matter if it’s you, your family, or your pet, if you suspect you or a loved one has been poisoned due exposure to plants, here is what to do:

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Did we miss anything? Do you know any other UK-growing poisonous plants? Let us know in the comments below or give us a shout on social media!