Passionflower (Passiflora) is a tropical vine thought to be native to the Amazon region of Brazil and Paraguay. Though over 60 species with edible fruits grow around the world, only two of these are grown for the fruit, which is both eaten raw and processed for juice. Several native North American species occur in warm regions of the United States, and while their fruits are also edible, they are valued primarily for their peculiar yet beautiful flowers.
Passiflora is the botanical genus name for the passionflower. The plant is best known for its extremely showy flowers, which can be as large as 5 inches across. Flowers are brilliantly colored and identifiable by the wavy, hair-like structures that ring the inner corolla, as well as by the distinctive, cross-shaped anthers which stand high above the flower. In its native tropical range, the vine is woody and evergreen, though United States native passionflowers are deciduous at the northern extremes of their ranges. Leaves are trident-shaped and are sometimes toothed or serrated.
Types of Passiflora
Two species of passiflora are grown commercially for fruit: the purple passionflower (Passiflora edulis) and a mutated, yellow variety of the same species (P. edulis flavicarpa). In the United States, the native passionflower or maypop (P. incarnata) is a sometimes evergreen, sometimes deciduous vine, and it is the easiest species to acquire through commercial retail operations. A native American yellow passionflower (P. lutea) is also sometimes available for sale.
South American passionflowers, being solidly tropical plants, are not hardy north of U.S. Department of Agriculture hardiness zone 9. Because they require a relatively humid climate, the plants' range in the northern hemisphere is essentially restricted to parts of Florida. Native American passionflowers will tolerate slightly colder conditions, growing in temperate climates through zone 7--the plant dies, however, back to the ground each winter, regenerating rapidly as warm weather returns.
Care and Culture
Passionflowers are best situated in full sun. The plant's preferred soil types are moderately moist, loamy to sandy soils, though most species will tolerate clay soils as well. Soils should also be slightly alkaline. Individual vines will grow to be 30 to 60 feet long, so plants should be given a fence or large trellis on which to climb. Because vines are aggressive growers with invasive potential, care should be taken to prevent their escape. Tropical passionflower is less drought tolerant than its native American cousin, which can withstand limited periods of dry weather.
Uses in the Garden
In hot, humid climates, where passionflower is evergreen, the plant is an excellent candidate for creating dense screens of lush, leafy growth; because it flowers throughout the summer and fall, such a screen would be punctuated by profuse blooms. The plant can also be used as a ground cover, as it will scramble along and cover with foliage any obstacle in its path. Passionflower attracts bees, hummingbirds and butterflies and is well suited for naturalized flower gardens.
As an added benefit, the egg-sized fruits, which mature throughout the summer and fall, are edible. Native passionfruit is less sweet than tropical varieties; nevertheless, the crunchy seeds encased within the plump, tart flesh make for an interesting treat on a hot summer day.