Passiflora incarnata, commonly known as maypop, purple passionflower, true passionflower, wild apricot, and wild passion vine, is a fast-growing perennial vine with climbing or trailing stems. A member of the passionflower genus Passiflora, the maypop has large, intricate flowers with prominent styles and stamens. One of the hardiest species of passionflower, it is a common wildflower in the southern United States.
The stems can be smooth or pubescent; they are long and trailing, possessing many tendrils. Leaves are alternate and palmately 3-lobed and occasionally 5-lobed, measuring 6–15 centimetres (2.4–5.9 in). They have two characteristic glands at the base of the blade on the petiole. Flowers have five bluish-white petals. They exhibit a white and purple corona, a structure of fine appendages between the petals and stamens. The large flower is typically arranged in a ring above the petals and sepals. They are pollinated by insects such as bumblebees and carpenter bees, and are self-sterile. The flower normally blooms in July.
The fleshy fruit, also referred to as a maypop, is an oval yellowish berry about the size of a hen egg; it is green at first, but then becomes orange as it matures. As with other passifloras, it is the larval food of a number of butterfly species, including the zebra longwing and Gulf fritillary. In many cases its fruit is very popular with wildlife. The egg-shaped green fruits 'may pop' when stepped on. This phenomenon gives the P. incarnata its common name.
The maypop occurs in thickets, disturbed areas, near riverbanks, and near unmowed pastures, roadsides, and railroads. It thrives in areas with lots of available sunlight. It is not found in shady areas beneath a forest canopy.
The Cherokee in the Tennessee area called it ocoee; the Ocoee River and valley are named after this plant, which is the Tennessee state wildflower. This, and other passionflowers are the exclusive larval host plants for the Gulf fritillary and non-exclusive for the variegated fritillary butterflies.
Passiflora incarnata is easily cultivated. The maypop in the wild is an aggressive vine and native to the southeastern United States extending into the central portion of the US reaching Illinois, Indiana, and Ohio. The plants grow in full sun and need direct sunlight for at least half of the day. The best soils for P. incarnata are well-drained  but the plants tolerate occasionally wet and acidic soils. The plants have a high drought tolerance. P. incarnata can be planted all the year in zone 7–11 (hardiness zone). The space between two plants is 36–60 inches (91.44 – 152.4 cm). One to two years are necessary before they begin bearing. Each flower has a very short life (about one day). Then the fruit develops in two to three months. The harvest depends on vine size and age of the plant but one reported 10–20 fruits per vine. Seeds can be collected in the fall after the fruit has begun to shrivel. There are some problems with nematodes and caterpillars in the culture of P. incarnata. The flowers appear to be perfectly suitable for bumblebee pollination. As the bees look for nectar, the pollen filled flower anthers brush the back of the bee and, when the bee moves to the next flower, the pollen is readily transferred to the central sticky stigma.
Passiflora incarnata can potentially become an agricultural weed. The genus Passiflora introduced for agricultural purpose has been reported as an important weed in certain regions of the world. The United States Department of Agriculture notes that P. incarnata is referred to as a weed by these publications: Weeds of Kentucky and adjacent states: a field guide and Weeds of the United States and Canada.
Historical uses and folk medicine
Historically, the plant has been used as an herbal medicine in the belief it may treat anxiety, insomnia, or hypertension.[non-primary source needed] Methanol extractions from the leaves has been reported to be an effective antitussive in mice. Passionflower is included in the national pharmacopeias of France, Germany, and Switzerland, and is also monographed in the British Herbal Pharmacopoeia and the British Herbal Compendium, the ESCOP monographs, the Community Herbal Monographs of the EMA, the German Standard Licences, the German Homoeopathic Pharmacopoeia, the Homoeopathic Pharmacopoeia of the United States, and the Pharmacopeia of Egypt. The botanical drugs included in the current European and British Pharmacopoeias are the dried aerial parts of the plant. In North America and South America, tea made from the roots is used as a tonic. In Australia, it is commonly believed to be a sedative and anxiolytic.
In traditional medicine, passionflower is reputed to have sedative effects as used historically in Europe, but in 1978, the U.S. Food and Drug Administration (FDA) prohibited its use in over-the-counter sedative preparations because it had not been proven safe and effective. When used in food manufacturing as a flavor, passionflower is included among substances approved by the FDA.
Passionflower is classified as generally recognized as safe (GRAS) for use as a flavor in foods in the United States, and possibly "can be used for the relief of mild symptoms of mental stress and to aid sleep." There is no evidence that P. incarnata has anti-disease activity.
P. incarnata may increase main effects or side effects of medications listed above.
For oral consumption, pregnant or breastfeeding women should use caution and seek medical advice before orally consuming P. incarnata. The effects of oral ingestion of the plant compounds on reproduction or on unborn child have not been tested. The oral consumption of this plant may prejudice the ability to drive and use machinery.
P. incarnata contains flavonoids and alkaloids, with leaves containing the greatest concentration of flavonoids. Other flavonoids present in P. incarnata include chrysin, apigenin, luteolin, quercetin, kaempferol, and isovitexin.
In cooking, the fruit of passionflower may be used for jam and jellies, or as a fresh substitute for its commercially grown South American relative, Passiflora edulis. The fruit can be eaten by hand, as indicated by its common name: liane de grenade or "pomegranate vine".
- "State Symbols". Tennessee Government. Retrieved October 24, 2011.
- Horn, compiled and edited by Dennis Horn and Tavia Cathcart ; technical editor: Thomas E. Hemmerly ; photo editors: David Duhl and Dennis (2005). Wildflowers of Tennessee, the Ohio Valley, and the Southern Appalachians : the official field guide of the Tennessee Native Plant Society. [Edmonton]: Lone Pine Pub. p. 105. ISBN 978-1-55105-428-5.
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- PLANTS Database. "Purple Passionflower". United States Department of Agriculture. Retrieved 22 November 2015.
- Haragan, P. D. (1991). Weeds of Kentucky and Adjacent States: A Field Guide. Lexington, KY: The University Press of Kentucky. ISBN 978-0-8131-3369-0.
- Southern Weed Science Society (1998). Southern Weed Science Society's weeds of the United States and Canada [electronic resource]. Champaign, Ill: Southern Weed Science Society.
- Plants For A Future: Passiflora incarnata
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