Tobacco
Interestingly enough, tobacco is poisonous, even if it’s the most commonly used plant in the entire world. But just because it’s popular, doesn’t mean it’s safe. It’s easy to grow tobacco in your backyard, and chances are, your heavily smoking neighbors might grow the plant. It’s known as a cardiac poison that’s also damaging to your lungs, brain, and teeth. This is probably the most poisonous plant on this list. It kills more than 5 million people every single year, which is why it’s the most poisonous. It doesn’t cause immediate fatalities like the other plants on this list, the damage from tobacco is slow-burning, exactly how you smoke it (Britannica).