The passion flower family includes more than 500 species. The family received its name in the belief the flowers of some species have a structure symbolic of the crucifixion, or passion of Jesus Christ. Some herbalists use passion flower to make a soothing tea, but parts of some species are also toxic.
This tropical species of the passion flower family is the most poisonous plant in the world, according to the University of Berkeley. Its tuberous roots include a deadly mix of cyanide and a slower-acting poison unique to this plant.
This climbing vine makes a tea used for insomnia and anxiety. According to prevention.com, some doctors say the passion-flower alkaloids could react badly with antidepressants, but there are no reports of this actually happening.
Prevention.com says passion flower appears to be safe if taken in recommended doses, but there is one unconfirmed report of a patient experiencing nausea and vomiting in response to taking passion flower.
Some species of passion flower have cyanide in their vines, leaves and unripe berries, enough to make someone sick from eating them.
There are no documented cases of poisoning from P. incarnata, but there have been no clinical trials to definitively determine if it's toxic.