1Oleander (Nerium Oleander)
A small child can experience symptoms after handling just one leaf from the plant, though typically it takes more contact for severe reactions to take place. Upon consumption, the poison causes intestinal issues like vomiting, diarrhea (sometimes bloody), excess salivation, and cramping/pain. It can also cause a racing, irregular heart rate, poor circulation, tremors, seizures, coma, and death.
In India, there are many cases of people consuming mashed Oleander seeds to attempt suicide. (Source 1 | Source 2 | Photo)
2Manchineel (Hippomane Mancinella)
In fact, it's not just the fruit (which does in fact resemble little apples) that is poisonous, but the entire tree is toxic to humans and animals. The tree oozes a white sap when it rains, so standing beneath the tree can cause blistering of the skin. Burning the tree releases extremely toxic fumes which can cause blindness and respiratory problems when humans come into contact with the smoke. Consumption is generally fatal, and it's, by all accounts, an agonizing death.
It is common for locals to mark the tree with signs or a red X on the trunk to keep people away. The sign on the tree above reads: "Warning! The leaves, bark, and fruits of these trees contain a caustic sap which may be injurious if touched. Columbus described the small green fruits as 'death apples.' The trees are common along the Caribbean shores. Avoid contact with any part of this tree!" (Source | Photo)
3Deadly Nightshade (Atropa Belladonna)
One of the most toxic plants in the Western Hemisphere, consumption of Deadly Nightshade leads to delirium, hallucinations, dilated pupils, sensitivity to light, blurred vision, tachycardia, loss of balance, staggering, headache, rash, dry mouth and throat, slurred speech, urinary retention, constipation, confusion, hallucinations, delirium, and convulsions. Without receiving the antidote, sufferers will eventually die due to the plant's disruption of their body's involuntary activities such as sweating, breathing, and heart rate. (Source | Photo)
That's because when they make castor oil they remove a lethal compound called ricin, making the oil safe to consume. While usually fatal, if consumption of the castor bean doesn't kill you, you can look forward to symptoms like nausea, emesis, diarrhea, tachycardia, hypotension and seizures, often persisting for up to a week. (Source | Photo)
5Water Hemlock (Cicuta)
6English Yew (Taxus Baccata)
Consumption of the Yew in even tiny amounts causes cardiac issues that result in death. It is quick-acting and there is no antidote. (Source 1 | Source 2 | Photo)
9Dumb Cane (Dieffenbachia)
10Jimson Weed (Datura Stramonium)
Also called devil's trumpet, angel's trumpet, devil's weed, stinkweed, locoweed, and hell's bells, people who attempt to consume this weed recreationally for the hallucinogenic properties often get more than they bargain for because it's nearly impossible not to overdose. In South Africa, they call them "mad seeds." (Source 1 | Source 2 | Photo)