Mother Nature’s poisonous plants to humans...
Monkshood (Aconitum napellus)
The most poisonous part is the roots, though the leaves can pack a punch too. Both contain a neurotoxin that can be absorbed through the skin. Early symptoms of poisoning are tingling and numbness at the point of contact or severe vomiting and diarrhea if it has been eaten. In 2010, a woman poisoned her lover using this plant. Apart from causing severe gastrointestinal upset, the poison slows the heart rate which can result in death.
Giant hogweed (Heracleum mantegazzianum)
These weeds are massive and pretty hard to miss when they are towering over you. The sap of the giant hogweed plant is phototoxic; when the contacted skin is exposed to sunlight or to ultraviolet rays it can cause severe skin inflammations. Initially, the skin colours red and starts itching.
Blisters form as it burns within 48 hours. They form black or purplish scars that can last several years. Hospitalization may be necessary. The presence of minute amounts of sap in the eyes can lead to temporary or even permanent blindness.
The manchineel tree (Hippomane mancinella)
Found in northern South America up to the Florida Everglades and throughout the Caribbean. In some parts of its range it’s painted with a cautionary red cross. They grow little green fruits that were once called the ‘little apple of death’ by Columbus.
The milky sap produced by this tree contains the powerful irritant phorbol. Just brushing past it can leave you with horribly scalded skin. Sheltering beneath it in a tropical shower can be disastrous too because even the diluted sap can cause an extreme rash. Burning down these trees is also a bad idea. The smoke from a burning manchineel can temporarily blind a person and cause significant breathing problems. While the effects are unpleasant, skin contact with this tropical tree can’t kill you. The real death threat comes from eating its small round fruit. Ingesting the fruit can prove fatal when severe vomiting and diarrhea dehydrate the body to the point of no return.
Now well known thanks to Walter White in Breaking Bad. This plant is used to make caster oil. After the laxative oil has been extracted the remaining residues of its mottled brown seeds contain a potent cocktail of toxins.
Ricin kills by interfering in cell metabolism, the basic chemical processes needed to sustain life. The creation of essential proteins is blocked, leading to cell death. Casualties can suffer vomiting, diarrhea and seizures for up to a week before dying of organ failure.