Passiflora, known also as the passion flowers or passion vines, is a genus of about 500 species of flowering plants, the namesakes of the family Passifloraceae.
They are mostly vines, with some being shrubs, and a few species being herbaceous. For information about the fruit of the passiflora plant, see passionfruit. The monotypic genus Hollrungia seems to be inseparable from Passiflora, but further study is needed.
The family Passifloraceae has a pantropical distribution. Passiflora itself is absent from Africa, where many other members of the family Passifloraceae occur (e.g. the more plesiomorphic Adenia).
Most species are found in South America, eastern Asia, southern Asia and New Guinea. Nine separate species of Passiflora are native to the United States, found from Ohio to the north, west to California and south to the Florida Keys. Four or more species are also found in Australia and a single endemic species in New Zealand. New species continue to be identified: for example, P. pardifolia and P. xishuangbannaensis have only been known to the scientific community since 2006 and 2005, respectively.
Some species of Passiflora have been naturalised beyond their native ranges. For example, blue passion flower (P. caerulea) now grows wild in Spain. The purple passionfruit (P. edulis) and its yellow relative flavicarpa have been introduced in many tropical regions as commercial crops.