The seeds of the castor bean plant contain ricin, a highly toxic protein that can be lethal if ingested.
All parts of the oleander plant, including leaves, flowers, and stems, contain cardiac glycosides that can cause serious cardiac issues if consumed.
Foxglove contains digitalis glycosides, which can be toxic and potentially fatal if ingested in large quantities.
Deadly nightshade contains tropane alkaloids that can cause hallucinations, delirium, and even death if ingested.
Water hemlock is one of the most toxic plants in North America, containing cicutoxin that can cause seizures and respiratory failure.
While birds can eat the berries of pokeweed, all parts of the plant, especially the roots and leaves, are toxic to humans and can cause nausea, vomiting, and diarrhea.
Angel's trumpet contains tropane alkaloids and can cause hallucinations, delirium, and dangerous changes in heart rate if ingested.
Also known as wolfsbane, monkshood contains aconitine, a highly toxic alkaloid that can cause severe cardiac and neurological effects.