Passiflora is a genus of flowering plants in the family Passifloracea, comprising about 500 species. It is commonly known as Passion Flowers or Passion Vines. The genus is mostly vines, some being shrubs and a few are herbaceous. Nine species of Passiflora are native to the USA, found from Ohio to the north, west to California and south to the Florida Keys. Seventeen are found in South America, China, and Southern Asia, New Guinea, four or more in Australia, and a single endemic species in New Zealand. Species of Passiflora have been naturalised beyond their native ranges, like the purple passionfruit (P.edulis) and P. flavicarpa have been introduced in many tropical regions as commercial crops.
Passiflora has unique flower structure, which in most requires a large bee to effectively pollinate. In the American tropics, wooden beams are mounted very near passion fruit plantings to encourage carpenter bees to nest. Other species are pollinated by hummingbirds (especially hermits like Phaethornis), bumble bees, wasps, or bats, some are self-pollinating. The Sword-billed Hummingbird (Ensifera ensifera) has elongated bill that has co-evolved with certain passion flowers, such as Passiflora mixta.
Yellow Passion flower (P. lutea) pollen is apparently the only pollen eaten by the unusual bee Anthenurgus passiflorae. However the bees collect the pollen, but do not pollinate the flowers.
Passiflora species are important sources of nectar for many insects. The leaves are used as food plant for larvae of some Lepidoptera species such as Swift moth (Cibyra serta), American Sarah Longwing (Heliconius sara) and Asian Leopard Lacewing (Cethosia cyane).
Caterpillars of the following butterfly species feed on specific Passiflora species.
Postman Butterfly (Heliconius melpomene) feed on P. menispermifolia and P. oerstedii
Zebra Longwing (Heliconius charithonia) feed on Yellow Passion Flower, Two-flowered Passion Flower (P. biflora) and Corky-stemmed Passion Flower (P. suberosa)
Banded Orange (Dryadula phaetusa) feed on P. tetrastylis
Julia Butterfly (Dryas julia) feed on Yellow Passion Flower and P. affinis
Gulf Fritillary (Agraulis vanillae) feed on Yellow Passion Flower, Stinking Passion flower (P. foetida) and Maypop (P.incarnata)
In order to prevent the butterflies from laying too many eggs on any single plant, some species of Passiflora bear small colored nubs which resemble the butterflies' eggs, and fool them to believe that more eggs have already been deposited on a plant than the actual case. Many passiflora species also produce sweet nutrient-rich liquid from glands of their leaf stems. The liquid attracts ants which will kill and eat the many pests that they happen to find feeding on the passion flowers.
Stinking Passion Flower (P. foetida) has bracts that are covered with hairs which exude a sticky fluid. Many small insects get stuck to this and get digested to nutrient-rich goo by protease and acid phosphate. Since the insects usually are rarely major pests, this Yellow Passion Flower seems to be a protocarnivorous plant.
Some species are invasive weeds, such as Banana Passion Flower (P. tarminiana) and Blue Passion Flower ( P.caerulea). They can overgrow and smother other vegetation and need to be watched so that unwanted spreading can be curtailed.
Many species have round or elongated edible fruits. P. edulis is cultivated extensively in the Caribbean and south Florida and South Africa for its fruits, which is used as a source for juice. Sweet Granadilla (P.ligularis) is also a wide-grown species in large parts of Africa and Australia. Maypop (P.incarnata) is a common species in southeastern US. It can withstand cold temperature of -4°F (-20°C) before its root die. The fruit is roughly the size of a chicken's egg, yellowish in color and sweet.
Plant Passiflora in full sun, in moisture-retentive but well-drained soil. Propagation in by seed in spring; semi-ripe cuttings in summer, or layer in autumn. Cucumber mosaic virus is known to attack the plant.