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Passionflower - Passiflora incarnata

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Passionflower (blooms)

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Passionflower (Passiflora incarnata) is a fast-growing perennial vine occurring from Virginia to southern Illinois and southeast Kansas, south to Florida and Texas. The genus Passiflora of the passionflower family (Passifloraceae), explodes in diversity in the American tropics with over 400 species, representing 95 percent of all passionflowers. There is only a handful of temperate climate species, including Passiflora incarnata.

What's in a name?
The common and genus names share the same origin - honoring the Passion of Christ (the period between the Last Supper and the death of Christ). The name is derived from flos passionis, a translation of fior della passione, a popular Italian name which was applied to the plant to signify religious symbolism. The floral structure was seen to symbolize the implements of the crucifixion. The three spreading styles atop the stigma were thought to represent the three nails by which Christ was attached to the cross. To some the five hammer-like anthers atop of the stamens exemplified the hammers used to drive the nails. To others, they represented Christ's five wounds. Beneath these floral structures is a fringe of colored filaments, known as the corona. It was believed to depict a halo or perhaps the crown of thorns. Beneath it sits the corolla -- with ten petals, each representing the ten apostles at the Crucifixion -- save Peter and Judas. Giacomo Bosio, an Italian ecclesiastic and historian, went so far as to interpret that the unopened, bell-shaped flowers held these sacred symbols from the view of heathens who had not yet been converted to Christianity. If that's not enough, the lobed leaves and long green vines were further thought to represent the hands and whips of Christ's prosecutors. And so, both the common and Latin names - passionflower (Passiflora) - honors these visions.

Thomas Johnson editor of the 1633 edition of Gerarde's Herball described these notions for what they were: "The Spanish Friers for some imaginarie resemblances in the floure, first called it Flos Passionis, The Passion floure, and in a counterfeit figure, by adding what was wanting, they made it as it were an Epitome of our Saviors passion. Thus superstitious persons semper sibi somnia fingunt" [always see contrived images] The species name "incarnata" means "made of flesh or flesh-colored."

Passionflower as food
In his "Thousand Mile Walk to the Gulf" John Muir speaks of the apricot vine (passionflower) as having a superb flower "and the most delicious fruit I have ever eaten." That delicious flavor apparently did not go unnoticed by Indian groups of the eastern United States.

In a 1989 study on Indian sites, K. J. Gremillion provides strong evidence for the prehistoric use of the fruits by Indian populations of North America, as well as evidence that by the time Europeans arrived, the plant was either consciously cultivated, or at least managed for fruit production around areas of Algonkian settlements in Virginia. The seeds are found at archaeological sites several thousand years old. She notes also that the human-plant relationship with passionflower may have contributed to helping to spread the plant's modern geographical range.

If you grow passionflower, you must taste the fruits. The fruits of the maypop ripen from yellowish to light brown in color. The slimy aril covering the seeds is very sweet and fruity when ripe. The hard seeds can be separated from the pulp through a sieve or apple sauce strainer. Or if you are in the garden, you can pop open the ripe fruit and suck the delicious pulp from the fruit. Make sure that the fruit is not over-ripe. Perfectly ripe fruits are delicious -- over-ripe fruits ferment into a foul paste.

Traditional uses
In America, passionflower is also known as maypop and apricot vine. Traditionally, the fresh or dried whole plant has been in herbal medicines to treat conditions of nervous anxiety. The earliest reference on American medicinal plants, Schoepf's Materia Medica Americana, a Latin work, published in Germany in 1787, mentioned use of the plant to treat epilepsy of the aged. Mostly absent from nineteenth century works on American medicinal plants, or mentioned only in passing, passionflower was introduced into medicine in 1839 or 1840 by Dr. L. Phares of Mississippi. The remedy remained buried in obscurity until Prof. I. J. M. Goss of Atlanta, Georgia, reintroduced it into the practice of Eclectic physicians in the late nineteenth century. Eclectic physicians used medicines largely made from American medicinal plants.

Dr. E. D. Stapleton writing in a 1904 issue of the Detroit Medical Journal summed up his experience in using passionflower tincture to treat insomnia "I would say that its action is best obtained in cases of nervousness due to causes other than pain-that it is slow in acting because it is not a narcotic, but a nervine and sedative. It relieves irritation of the nerve-centers and improves sympathetic innervation, thus improving circulation and nutrition, and is as a rule sure in its results-no bad after-effects, no habits formed".

Harvey Wickes Felter and John Uri Lloyd wrote in 1898, "Its force is exerted chiefly upon the nervous system, the remedy finding a wide application in spasmodic disorders and as a rest-producing agent. It proves specially useful in the insomnia of infants and old people. It gives sleep to those who are laboring under the effects of mental worry or from mental overwork."

Pharmacists only recognized the value of the plant in the twentieth century. The dried flowering and fruiting tops of Passiflora. incarnata were listed in National Formulary from 1916 to 1936. Formerly approved as a sedative and sleep aid over-the-counter drug, it is no longer recognized as effective by FDA after a 1978 review of night-time sleep aids. This is not because the FDA evaluated the herb and found it wanting in medicinal value, rather industry was responsible for submitting data on safety and efficacy of nonprescription drugs during the review process. No American company came forward in support of the medicinal value of passionflower, hence it was dropped. Consequently, passionflower is yet another native American plant that is more widely researched and used in Europe than it is in the United States.

Current use
The fresh or dried whole plant as well as their preparations are accepted for medicinal use in Germany, France, and other European countries for the treatment of nervous anxiety, in daily dosages equivalent to 0.5 to 2 g. of the herb, or 2.5 g in tea (about a teaspoon of the dried, ground herb). Preparations include tea, tinctures, fluid extracts, solid extracts, and even sedative chewing gums. Passionflower is also combined with valerian and hawthorn in products used in Europe to treat digestive spasms, gastritis, and colitis.

A number of chemical components have been identified from the leaves including flavonoids, small amounts of maltol, coumarin derivatives, a small amount of an essential oil and trace amounts of a potentially toxic alkaloid group called harmala alkaloids. Plant material used in European phytomedicines is analyzed to see that it contains at least 0.8% total flavonoids, and less than 0.01% harmala alkaloids. Standardized passionflower products contain flavonoids as the primary chemical marker. While flavonoids are generally considered among the most active components of the plant, scientists cannot attribute passionflower's sedative action to a single chemical compound or group of compounds. Once again, mother nature's complexity defies unraveling.

In 1988, Italian researchers published on research of an extract of P. incarnata for its potential neuropharmacological properties. Oral administration and injections into the peritoneal cavity of rats decreased brain stimulus in a number of pharmacological models. The later route of administration also significantly prolonged sleeping time and protected animals from the convulsive effect of chemical test models. Locomotor activity was also reduced by the extract. Active components were ascribed to both water soluble and alcohol soluble chemical fractions. However, the activity could not be attributed to either the alkaloids or flavonoids in the extracts. While a number of chemical components have been considered among the plant's active components, attribution to its neuropharmacological properties has not been clearly determined. These authors suggest that future research should attempt to evaluate possible relationships with central nervous system neurotransmitters.

Pharmacological studies by various European research groups have shown that passionflower preparations have antispasmodic, sedative, anxiolytic (allaying anxiety) and hypotensive activity. One Italian research group tested passionflower both alone and in various combinations with other herbs which were considered to have a sedative activity. A synergistic association of sedative activity at high dosage was observed. Other researchers have found that one component of passionflower (passicol) has antimicrobial and antifungal activity.

In European phytomedicine, passionflower is used for states of nervous tension, especially in cases of sleep disturbance or exaggerated awareness of heart palpitations at doses ranging from 0.5 to 2 g of the herb and 2.5 g of the herb in infusion (tea), taken three to four times a day. No toxicity has been observed in laboratory animals, and they also showed no adverse effects of passionflower extracts administered intravenously in mice. The German monograph on passionflower lists no known contraindications, side effects or drug interactions.

The Future

While various pharmacological studies have confirmed sedative, antispasmodic, and anxiolytic activity at various doses of several chemical fractions, definitive attribution to a single active component has not been achieved. Research to date on passionflower extracts points to a synergistic activity of several chemical components. Unfortunately, well-designed clinical research on passionflower extracts are notably absent from the literature, except for a handful of studies involving passionflower in combination with other phytomedicines. Here, clinical experience provides some insights. In his textbook Herbal Medicine Rudolf Fritz Weiss (1988) notes that Passiflora is mildly sedative and hypnotic, but is best used as a supportive ingredient in herbal preparations containing other ingredients.

In Europe, passionflower products are widely prescribed as sleep aids. Most of the supply of dried leaves, either cultivated or wild-harvested in North America goes to the European market. The long-standing success reported in clinical cases, coupled with its safety and historical reputation, merit intensified research to discover passionflower's exact mechanisms of action and optimum applications.

Growing Passionflower

While passionflower is commonly regarded as a southern plant, it will grow as far north as the Boston area, and I suspect, if placed in a well-protected situation and mulched through the winter, it would even survive as a perennial in central Maine. Here in the Arkansas Ozarks, the native passionflower withstands temperatures of -25° F. without any protection. When purchasing seeds or plants, it's probably a good idea to at least inquire where the plant material originated -- if the seller knows. Obviously, passionflower seeds or plants from south Florida are less likely to survive in New England, than plants originating from more northerly areas.

While dying back to the ground each year, it makes a marvelous fast-growing climbing cover for a fence, or can be trained on a trellis as a focal point for the herb garden. In the South it will grow 20-30 ft. in a single season. In more northerly areas, expect a growth of about 15 feet in a season. Passionflower grows in waste places, thriving in relatively poor, sandy, acidic soils. Good drainage is essential. Full sun is necessary.

Propagation is by seeds, cuttings, or layering. Cuttings about six inches in length can be taken from mature plants, then rooted in sand. Passionflower grows readily from seed -- if one is patient. After harvesting the fruits, clean out the seeds from the muclaginous fleshy aril surrounding them, then dry in the shade. Plant the following spring in light soil, preferably in flats, where they can be looked-after more easily. They may germinate late in the summer, or may sit dormant until the following spring. The experience of many who try passionflower from seed for the first time is disappointment, born of expectations that the seeds will germinate in a couple of weeks. Wait a year if you have to. The result of your patience and suspense will be worth it a few years later.

In the May/June 1989 issue of Fine Gardening, frequent Herb Companion contributor, Dr. Arthur O. Tucker, described his technique of starting passionflowers from cuttings. He takes cuttings in September and roots them in perlite in 8-oz. Styrofoam cups, with holes punched in the bottom. After dipping them in a rooting hormone/fungicide he places them in a warm north-facing window for 2-3 weeks, until they root. He then re-pots them, and gradually moves them to a sunny location, until they are well established.

Propagation by layering can be achieved simply by removing the leaves from a small section of a stem in late summer, placing a portion beneath the soil, with a leafy end sticking out of the ground. Water well, and in a few weeks, the buried stem should produce roots. But wait. Keep the layer in the ground through the dormant months, allowing it to develop a full root system before transplanting. The layered cutting can be severed from the mother plant and placed in a new location. With a little luck and persistence, you will soon have your own passionflower planting. Of course, the easiest technique is simply to buy plants from a nursery.

References:

  1. Blumenthal, M. ed., S. Klein, trans. German Commission E Therapeutic Monographs on Medicinal Herbs for Human Use. (English translation). Austin, Texas: American Botanical Council, (in edit), 1997.
  2. ESCOP. Proposals for European Monographs on the Medicinal Uses of Passiflorae Herba. Meppel, The Netherlands: European Scientific Cooperative for Phytotherapy, 1992
  3. Felter, H.W. and J. U. Lloyd. King's American Dispensatory. 2 vols. reprint ed. 1983. Portland, OR: Eclectic Medical Publications, 1898.
  4. Foster, S. The Herb Companion (August/September): 18-23, 1991.
  5. Gremillion, K. J. The Development of a Mutualistic Relationship Between Humans and Maypops (Passiflora incarnata L.) in the Southeastern United States. Journal of Ethnobiology. 9(2):135-158, 1989
  6. Hoch, J. H. 1934. The Legend and History of Passiflora. American Journal of Pharmacy. (May, 1934): 166-170.
  7. Olin, B.R., ed. Passion Flower. The Lawrence Review of Natural Products. (May), 1989.
  8. Speroni, E. and A. Minghetti. Neuropharmacological Activity of Extracts from Passiflora incarnata. Planta Medica. 54: 488-491, 1988.
  9. Weiss, R.F. Herbal Medicine (translated from German by A.R. Meuss). Beaconsfield, England: Beaconsfield Publishers Ltd., 1988.
 
       
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