Passifloraceae, the Passion Fruit family
Perhaps disappointingly, the passion fruit has nothing do do with carnal desire, and to the best of my knowledge, is not an aphrodisiac. The name originated with a group of priests in South America, who stumbled across an odd-looking flower with five petals, sepals and stamens. They used the flower to illustrate Christ' Passion, in the same way that St. Patrick is said to have used the shamrock to explain the Church's trinity doctrine.
...the corona represents the crown of thorns; the styles represent the nails used in the Crucifixion; the stamens represent the five wounds; and the five sepals and five petals represent 10 of the apostles, excluding Judas, who betrayed Jesus, and Peter, who denied him three times on the night of his trial. Encyclopædia Britannica
Physical features
The plants themselves are extremely variable, ranging from ground and climbing vines, through shrubs, to trees. Although there are over 600 species, only around 60 bear edible fruit. Most are found in tropical America or Africa, although some of the Adenia genus are found in Asia.
The leaves of all species are finely toothed, alternate and stipulate. The flowers are radially symmetrical, and can be male, female, or bisexual, dependent on species. The flowers of most species have a gynophore or androphore (a structure in the centre of the flower that carries the reproductive parts). All of the passion-flower family have an additional cluster of threadlike structures in the flower, known as the corona. Most have five sepals, petals, and stamens, but the number can vary between three and five. The flowers usually have a one-chambered, ovary with numerous ovules attached to the inner walls, and most have seeds with an aril (a fleshy structure).
The fruits themselves are round, 1½ to 3 inches across, with a thick, tough rind, ranging from dark purple a light yellow colour. Inside the cavity are a large number of tiny capsules, filled with a fragrant orange juice and up to 250 small, hard, dark-coloured seeds. The flesh itself is fragrant, musky and smooth.
Commercial Growth
The major crop species are: giant granadilla (Passiflora quadrangularis); sweet calabash or pomme d'or (Passiflora maliformis); the yellow granadilla (Passiflora laurifolia); and the purple granadilla (Passiflora edulis).
Commercially, the fruit is primarily grown in the Brazil, the Caribbean and Australia for export to the West. The growth of interest in exotic fruits continues, and both the fruit and its juice are in high demand. Sadly, as with many cash crops, the growers have the worst of the deal, although on many Caribbean islands, growers have formed co-operatives to grow, market and transport the crop to maximise gain for themselves.
There has been some interest in the medicinal value of the fruit, as a glycoside known as passiflorine has been used as a sedative, and in some parts of the world, the juice is given as a digestive stimulant and treatment for gastric cancer.
http://www.hort.purdue.edu/newcrop/morton/Passionfruit.html
http://aggie-horticulture.tamu.edu/PLANTanswers/flowers/passionflr.html
Encyclopædia Britannica