12. Water Hemlock
Alderleaf Wilderness College lists water hemlock as one of the deadliest poisonous plants in North America. Within 15 minutes to six hours of eating water hemlock, cicutoxin can cause seizures, nausea, vomiting, frothing at the mouth, and pupil dilation. Death can occur within hours. According to the U.S. Forest Service, water hemlock can be found throughout the United States and Canada.
11. Lily of the Valley
All parts of the lily of the valley plant are poisonous. However, the sweet, red berries most commonly cause poisoning, as they are attractive to small children. According to Colorado State University, the cardenolides in this plant are similar to digitalis. Symptoms of poisoning from lily of the valley include vomiting, diarrhea, rapid heart rate, arrhythmias, and death.
The stalk of the rhubarb plant makes a sour, yet tasty, addition to desserts such as rhubarb crisp or strawberry rhubarb pie. However, the leaves of the rhubarb plant are high in oxalic acid, which can cause kidney problems when eaten. Eating a large number of these leaves could kill you. Furthermore, mistakenly including smaller amounts of these leaves in your salad can cause stomach upset.Related: 7 Indoor Plants That Can Survive with Little Light