Passion flower plants are members of the genus Passiflora, which literally means "passion flower." They get their name from the early Spanish New World missionaries, who interpreted symbolism in the flower shapes and related them to the crucifixion of Jesus, also known as the Passion. These odd-looking flowers are very colorful. Along with the tropical foliage, they add an exotic flare to a garden.
Most types of passion flower vines are native to South America and Central America north to the southern part of the United States. They have been spread by man to every continent except Antarctica. Most species are tropical or subtropical and cannot survive any freezes. A few types that come from northern climates are partially cold-resistant.
Most passion flower plants are vines. A few rare species grow as shrubs or trees. They all have lobed leaves, usually with three lobes, sometimes with five. On the leaf stem of most species are protruding glands. The vine climbs by using tendrils that wrap around anything they touch. They are very fast growers. Plants that grow in warm areas have woody stems; plants in cool areas may die to the ground in the winter then sprout back with herbaceous stems in the spring.
Most passion flowers are tropical and only suitable for southern Florida or Hawaii. Some species can grow in the southern United States and will survive in areas that do not get below 20 degrees in the winter. They like a well-draining rich soil and prefer to dry out slightly between waterings. Because they are a vine, they need a sturdy support to grow on. Plant them in full sun.
Passion flower plants can be used to grow along a fence or on trellises. The fruit of most species are edible. They can grow in containers and can overwinter or be brought indoors during cold spells. In many parts of the United States, Passiflora incarnata is considered a weed species.
Scientists estimate that there are more than 500 different species of passion flower and numerous registered hybrids, many of which have disappeared from cultivation. The most common species in the United States is P. incarnata, also known as Maypops because the fruit makes a popping noise when stepped on. The species that produces the most commercial passion fruit is P. edulis.