The terms "Maypop" and "Purple Passion Flower" are often used interchangeably, but they refer to specific, closely related entities within the *Passiflora* genus. From a botanical perspective, understanding their relationship clarifies the difference.
The primary distinction lies in taxonomy versus colloquial naming. *Passiflora incarnata* is the accepted botanical species name. "Maypop" is the most common vernacular name for this specific species, derived from the hollow, popping sound the ripe fruit makes when crushed. "Purple Passion Flower," however, is a broader common name that can refer to *Passiflora incarnata*, but is also frequently applied to other passion flower species with purple blooms, most notably the tropical *Passiflora edulis* (grown for its fruit, the passion fruit) and the ornamental *Passiflora caerulea*. Therefore, all Maypops are a type of Purple Passion Flower, but not all Purple Passion Flowers are Maypops.
While similar, the species have identifiable differences. *Passiflora incarnata* (Maypop) is a herbaceous perennial vine that dies back to its roots in winter. Its flowers are typically 2-3 inches in diameter with white and purple petals and sepals, and a prominent corona of pinkish-purple filaments. Its fruit is an oval, yellow-green berry when ripe. In contrast, *Passiflora edulis* is a woody, evergreen vine in tropical climates. Its flowers are often larger and feature a more stark white and deep purple coloration. Its fruit is the well-known commercial passion fruit, which is typically dark purple or yellow and round to oval. The leaves of *P. incarnata* are three-lobed and serrated, while those of *P. edulis* are three-lobed but glossier.
This is a key differentiating factor. The Maypop (P. incarnata) is native to the southeastern United States and is remarkably cold-hardy, surviving winters in USDA zones 5-9. It is a resilient plant that spreads via root suckers. Other species commonly called "Purple Passion Flower," such as P. edulis and P. caerulea, have different origins. P. edulis is native to southern Brazil and Paraguay and is frost-tender (zones 9-12), while P. caerulea, native to South America, is slightly hardier (zones 7-10) but still less cold-tolerant than the Maypop.
The Maypop is an important native plant in its range, serving as a host for the larvae of Gulf Fritillary and other butterfly species. It is valued in native landscaping for its drought tolerance and ecological benefits. The other purple-flowered species are primarily grown for fruit production (P. edulis) or as fast-growing, showy ornamental vines (P. caerulea) in suitable climates, where they may not have the same native ecological integration.
