They are 3 to 8 inches long, deep green and glossy above, paler and dull beneath and, like the young stems and tendrils, tinged with red or purple, specially in the yellow form. It also has 5 stamens with large anthers, the ovary and triple-branched style forming a prominent central structure. Purple passion fruit is self-fruitful, but pollination is best under humid conditions. The flowers of the yellow form are perfect but self-sterile. Carpenter bees are the most efficient pollinator, much more so than honey bees.
Wind is ineffective because of the heaviness and stickiness of the pollen.
The flowers can also be hand pollinated. Within is a cavity more or less filled with an aromatic mass of double walled, membranous sacs containing orange-colored, pulpy juice and as many as 250 small, hard, dark brown or black, pitted seeds. Numerous hybrids have been made between purple and the yellow passion fruit, often yielding colors and other characteristic intermediate between the two forms. The vine, especially the yellow form, is fast-growing and will begin to bear in 1 to 3 years. Ripening occurs 70 to 80 days after pollination.