Passion flower (Passiflora incarnata) is a climbing vine with white and purple flowers and is native to the southeastern United States and Central and South America. It's been traditionally used to help with sleep.
People use passion flower for anxiety, including anxiety before surgery. Some people also take passion flower for insomnia, stress, ADHD, pain, and many other conditions. But there is no good scientific evidence to support these uses. In some foods and beverages, passion flower is added for flavoring.