A Guide to Australia’s Most Poisonous Plants

Certain Australian plants produce toxic substances as a defence mechanism against predators. 

It’s probably not something you think about often, but did you know that there are around 1000 plants in Australia that are poisonous to humans and animals?

Certain plants produce toxic substances as a defence mechanism against predators. 

As a gardener, it’s important to be aware of common plants that may be toxic so that you can take precautions to protect yourself and your family and pets from accidental poisoning.

Here’s a list of the most poisonous plants in Australia.

Angel’s Trumpets (Brugmansia)

Angels Trumpets Brugmansia | Plant varieties

The stunning large fragrant flowers of the Brugmansia are truly a sight to behold. But don’t be fooled by the lovely appearance of this tree or shrub as the leaves and seeds are highly toxic.

They contain dangerous alkaloids such as hyoscyamine and scopolamine. These can cause migraines, confusion, diarrhoea, and paralysis if consumed. In severe cases, they can even cause death.

Black Bean (Castanospermum australe)

Black Bean Castanospermum australe | Plant varieties

This tree is native to New South Wales and Queensland. It grows well in coastal rainforests and thrives in the moist soil along the banks of rivers. It’s also a valuable source of timber.

But, the seeds of the black bean are toxic and can cause diarrhoea and vomiting if consumed.

Castor Oil plant (Ricinus communis)

Castor Oil plant Ricinus communis | Plant varieties

This large flowering shrub has toxic leaves, flowers and seeds. If ingested they can cause nausea, vomiting, abdominal pain and diarrhoea.

Coral Tree (Erythrina)

Coral Tree Erythrina | Plant varieties

This rainforest tree has toxic bark, leaves and seeds. Ingestion of any parts of this tree can result in shortness of breath and lightheadedness.

It can also cause pale and blue skin as a result of a lack of oxygen in the blood.

Deadly Nightshade (Atropa belladonna)

Deadly Nightshade Atropa belladonna | Plant varieties

If you’ve ever read an Agatha Christie novel, you would be familiar with the deadly nightshade or belladonna. 

This plant is highly toxic and can cause hallucinations, hysteria, delirium and erratic behaviour. The ingestion of just one leaf or a handful of berries can be fatal. 

Remember that potato and tomato plants are also part of the nightshade family. Only the tubers of potatoes and the fruits of tomatoes are safe to consume. 

That’s why it’s important to always wash your hands after working with these plants or to wear gloves to keep yourself safe.

Gympie Gympie (Dendrocnide moroides)

Gympie Gympie Dendrocnide moroides | Plant varieties

This tree is a member of the nettle family. The leaves, stems and fruit of the tree have stinging hairs.

These are known to cause extreme pain, swelling and allergic reactions when they come into contact with the skin.

Milky Mangrove (Excoecaria agallocha)

Milky Mangrove Excoecaria agallocha | Plant varieties

This plant is commonly found in the coastal areas of New South Wales, Queensland and Western Australia. When cut, the wounds exude a milky sap that is highly toxic.

The sap has been known to cause temporary blindness as well as skin irritation and even blistering.

Nettles (Urticaceae)

Nettles Urticaceae | Plant varieties

There are many species in the nettle family. We even have a native species here in Australia in the genus Laportea.

It’s important to always wear gloves when removing any nettles from your yard as the leaves have small stinging hairs that can cause excruciating pain when they come into contact with the skin.

Oleander (Nerium oleander)

Oleander Nerium oleander | Plant varieties

The oleander is a common plant used in landscapes right around the country. But, I definitely wouldn’t have this in my garden.

Not only can the foliage cause skin irritation, but if consumed, just a single leaf can be fatal.

If you have this in your garden and want to remove it, don’t burn it as the smoke can emit fumes that are dangerous to your health.

Spurge (Euphorbia)

Spurge Euphorbia | Plant varieties

Euphorbias are common plants that many gardeners like to grow. However, it’s important to handle these plants with care, especially when pruning.

This is because they contain a sap called latex. This is highly toxic and can cause extreme inflammation of the mouth, nose and eyes. It can even cause blindness. 

Make sure you wear gloves when handling these plants and always wash your hands with soap and water after you’ve finished gardening.

Strychnine Tree (Strychnos nux-vomica)

With a common name like the Strychnine tree, you would expect this tree, which is native to Australia and South East Asia, to be poisonous. 

Once again, it’s the seeds of this tree that are toxic. In fact, these seeds contain a neurotoxin that can affect the nervous system resulting in convulsions and paralysis. This can eventually lead to death.

Additionally, the bark and flowers of the tree contain both strychnine and brucine. These are commonly used in rat poison.

Rhus Tree (Toxicodendron succedaneum)

Rhus Tree Toxicodendron succedaneum | Plant varieties

This is another tree that is native to Australia, New Zealand and Asia.

Contact with any part of this tree can initiate an allergic reaction and cause blisters and itchiness in the skin that can last for over a week.

Photo of author

Annette Hird

Annette Hird is a gardening expert with many years of experience in a range of gardening related positions. She has an Associate Diploma of Applied Science in Horticulture and has worked in a variety of production nurseries, primarily as a propagator. She has also been responsible for a large homestead garden that included lawn care, fruit trees, roses and many other ornamental plants. More recently, Annette has concentrated on improving the garden landscape of the homes that she has lived in and focused a lot of energy on growing edible plants as well. She now enjoys sharing her experience and knowledge with others by writing articles about all facets of gardening and growing plants.


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