Perhaps the most famously lethal on our list is
According to the Guinness Book of World Records, based on the amount of poison it takes to kill a human, the most poisonous common plant in the world is the castor bean (Ricinus communis).
Toxicity. D. moroides is notorious for its extremely painful sting which may leave victims suffering for weeks or even months. It is reputed to be the most venomous plant in Australia, if not the world.
Poisonous plants include poison oak, daffodils, and giant hogweed. Touching some plant saps, stems, or leaves may cause a skin rash. Parts of many plants may lead to severe gastrointestinal upset if eaten. Ingesting some plants may result in heart problems or nervous system issues.
Known colloquially as the gympie gympie (from the Gubbi Gubbi/ Kabi Kabi name for the plant, gimpi gimpi), gympie stinger, and giant stinging tree (D. excelsa), this plant has the dubious honour of being arguably the most painful plant in the world.
sensitive plant, (Mimosa pudica), also called humble plant, plant in the pea family (Fabaceae) that responds to touch and other stimulation by rapidly closing its leaves and drooping.
Known as Gympie-gympie in Australia and salat in Papua New Guinea, contact with this leaf can result in human death, more often extreme pain that can last for months. Stinging hairs deliver a potent neurotoxin when touched. Leaf has medicinal purposes in some PNG tribes. Scientific name is Dendrocnide moroides.
Botulinum toxin, the nerve agent commonly called botox, is best known for its miraculous effect on wrinkles.
Blue death is extremely poisonous and can be fatal to humans.
Pink oleander (Nerium oleander)
Yellow oleander (Thevetia peruviana)
These plants are mainly found in warm climates or in coastal gardens. Yellow oleander is different to pink oleander (Nerium oleander) which is commonly found in Sydney, Australia. Pink oleander is also considered poisonous.
Poison ivy has a wide range in its native North America from Mexico to southern Canada, and could be cultivated in the southern part of South Australia. It has never been found growing wild here, but may be able to escape in the higher rainfall regions.
Deadly Nightshade (Atropa belladonna)
Nightshade contains atropine and scopolamine in its stems, leaves, berries, and roots, and causes paralysis in the involuntary muscles of the body, including the heart. Even physical contact with the leaves may cause skin irritation.
The manchineel (aka Hippomane mancinella, aka the Tree of Death) is native to coastal areas in southern North America, such as South Florida, as well as the northern reaches of Central and South America and the Caribbean.
Foxglove (Digitalis purpurea) is a common garden plant that contains digitalis and other cardiac glycosides. These chemicals affect the heart. Foxglove is poisonous, although recorded poisonings from this plant are very rare.
Thallium is tasteless and odorless and has been used by murderers as a difficult to detect poison.
Nitrates and nitrites are abundant in the environment and are found in medicines and products in the home. Overexposure to nitrates and nitrites can lead to a condition called methemoglobinemia in which the body is deprived of oxygen, causing a blue-gray discoloration of the skin.
The concentration of borax in many ant baits is only 5.4%, so only small amounts of the active ingredients are present. Fipronil, avermectin, and indoxacarb all have the potential to affect the nervous system in humans. Ingestion of large amounts can cause weakness, dizziness, or a comatose state.
It is called the “silent killer” because it is colorless, odorless, tasteless and non- irritating. If the early signs of CO poisoning are ignored, a person may lose consciousness and be unable to escape the danger. More people die from carbon monoxide exposure than any other kind of poisoning.
1. Botulinum (ingested) It's hard to rank the lethality of toxins, but experts agree that botulinum – several orders of magnitude deadlier than sarin – is the gold standard. Your nervous system fails and you die in extreme pain.
Tetrodotoxin interferes with the transmission of signals from nerves to muscles and causes an increasing paralysis of the muscles of the body. Tetrodotoxin poisoning can be fatal.
If something hurts humans, we react instinctually to it—“fight or flight”—as do other animals. But plants don't have that ability—nor do they have nervous systems or brains—so they may have no biological need to feel pain.
Given that plants do not have pain receptors, nerves, or a brain, they do not feel pain as we members of the animal kingdom understand it. Uprooting a carrot or trimming a hedge is not a form of botanical torture, and you can bite into that apple without worry.
The sting lasts as long as the hairs remain below your skin; until your body physically forces them out. The pain from broken hairs can last for days to months. Photo of a gympie-gympie plant.