The rosary pea, with its vibrant red and black seeds, may look like a tempting addition to your jewelry collection. However, these seeds contain a highly toxic substance called abrin, which can be fatal if ingested. In fact, just one seed is enough to kill an adult human.

The castor bean plant, which is commonly used to make castor oil, is another plant that should be avoided at all costs. The seeds of this plant contain ricin, a highly toxic substance that can cause severe illness or death if ingested.

Poison sumac is a plant that is commonly found in swampy areas of the eastern United States. Like its relatives, poison ivy and poison oak, poison sumac contains an oil called urushiol that can cause a severe allergic reaction if touched.