Passionflower: Ecology, Cultivation, Botany, and Medicinal and Edible Uses

Passiflora incarnata, Passifloraceae

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If you have been following my blog or studied with me, you know I am interested in plant relationships in all their various forms, and not just plant/human relationships. Often when I am teaching, a student will interrupt my ramblings on ecology, botany, or cultivation to ask the proverbial “But what is it used for?” This cut-to the-chase question somehow smells of skipping romantic courtship. Granted, it is human nature to wonder how we might utilize a plant for medicine, food, fiber, clothing, art, etc. Our survival has always depended on this innate practical curiosity.

Passionflower is ecologically intriguing, drop-dead gorgeous, and an incredibly useful herbal medicine and wild edible. So I introduce this passionflower materia medica with some ecological, botanical, and cultivation snippets specific to this amazingly charismatic native vine, and hope that you wont skip this juiciness for the medicinal information.

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Ecology

Many plants produce extrafloral nectaries (nectar-producing glands located outside of the flower) on leaves, petioles, flower buds, bracts, and stems. The plants attract the ants with their sugary exudate, and the ants return the favor by protecting the plant from insects and other animals, that would otherwise eat it. (See the photos below of ants feeding on the extrafloral nectary of a peony flower bud.)

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Ants on a peony flower bud feeding off the extra-floral nectaries

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This plant-ant mutualism is so important to certain species of plants that their survival is contingent on the presence of their little bodyguards. Some ants even go so far as to girdle the twigs of neighboring plants that might otherwise outcompete their plant friend. Passionflower produces extrafloral nectaries at the base of the leaf, on the very top of the petiole (leaf stalk), and at the base of the flower, on the little green bracts (leaf-like appendages below a flower or group of flowers) below the petals (pictured below is an ant feeding off the extra-floral nectaries on the bracts below the flower bud). If you spend enough time with the plant you will see the ants crawling over the plant and pausing periodically to feed at the nectaries.

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Ant sipping nectar at an extra-floral nectary on the bract of a passionflower bud

Ant sipping nectar at an extrafloral nectary on the bract of a passionflower bud

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Passionflower leaves (Passiflora spp.) are the only food source for gulf fritillary caterpillars (Agraulis vanillae, Nymphalidae). Other butterfly larvae also feed on passionflower leaves, in the photo below is the variegated fritillary (Euptoieta claudia, Nymphalidae). Pictured below is the mature gulf fritillary butterfly nectaring on the flowers of matrimony vine (Lycium carolinianum, Solanceae) in Florida.

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Variegated fritillary caterpillar

Gulf fritillary butterfly nectaring on matrimony vine

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We have fritillary caterpillars on our passionflower nursery plants every year; the presence of patchy half-devoured leaves doesn’t exactly increase their salability. The caterpillars are like coyotes in a watermelon patch, or raccoons in a field of ripe corn – they eat just a little from each leaf and move on to a new leaf. We collect the caterpillars and create a mini habitat for them, feeding them whole passionflower leaves, until they metamorphosize into butterflies.  We release the gorgeous fritillaries into the garden, which will likely lay eggs on our passionflower leaves and start the whole process anew. Why would I release them back into the garden and let them eat my passionflower vines again? The fritillary butterflies have graced the skies of this beautiful country long before my ancestors ever stepped foot on this continent, and I am no killer of exquisitely colored native butterflies-to-be.

Adding another twist to the insect dance of passionflower, the ants will eat or pick off  butterfly eggs and dump the wee caterpillars overboard. I have noticed in my own garden that caterpillars do not eat up the vines supporting a healthy population of ants.

Passionflower medicinal leaves

Cultivation

Passionflower is very easy to grow, in fact in can be quite rambunctious if consumption does not outpace its exuberance. The vine is cold hardy to zone 6 (zone 5 in sheltered locales), and needs a trellis, wall, fence, or plant to climb up to reach its full glory. It often thrives for several years sending up new shoots far from the parent vine with its copious runners, and then the whole colony will up and die. Its disappearance is not related to the coldness of the winter, it appears to be a short-lived perennial, or perhaps very sensitive to mean looks. Passionflower prefers full sun and is relatively drought tolerant, but will flower in part shade, albeit more demurely. Last year we grew gotu kola (Centella asiatica, Apiaceae) and jiaogulan (Gynostemma pentaphyllum, Curcubitaceae) in the shade created by a tee-pee bamboo trellis covered by a passionflower vine. For more on germinating passionflower seeds, see my article, Passionflower, from seed to fruit and back again.

Botany

Passionflower’s floral arrangement is so unique that early Christian missionaries decided to capitalize on its distinctive morphology, and use it as an educational tool in describing Christ’s crucifixion. The name describes the passion of Christ and his disciples, although in addition, it does excite passion in laboratory mice, who have demonstrated increased mounting of non-estrus females. {vi} But alas, we digress from botany. The flowers have the standard sepals and petals; additionally they have a third floral whorl, the corona. Passionflower’s corona resembles purple and white striped threads, which vary depending on the variety or cultivar. As the flower opens these corona threads emerge in a beautiful crimped pattern (as seen in many of the photos in this article).

Passionflower corona close-up

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Above the corona rises the androgynophore (translates to male-female-bearing), which is the shared female and male reproductive structure. Rising above the short stalk, there are the five stamens (male, bearing pollen). Above the stamens rests the pistil, which is the female part of the flower; the pistil is comprised of three parts: the ovary, resembling a green ball, giving rise to the three styles and stigmas (female).

Passionflower has an interesting floral reproductive strategy: on any given plant, some flowers will be functionally bisexual (with fertile male and female parts), and some plants will be functionally male (with both male and female parts present, but only the male is functioning reproductively).[i] The term for this strategy of bearing both bisexual flowers and male flowers on the same plant is andromonoecy. The functionally bisexual flowers have styles, which recurve, bending down close to the stamens, so the pollinator can easily brush up against both the stamen and the stigma as it nestles its way into the nectar, produced at the base of the corona. (See the picture below for a view of passionflower pollination in action in a functionally bisexual flower. Those with prudish or tender constitutions may want to scroll quickly past this photo, as it is a tad racy.)

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Many other plants have this built in reproductive flexibility, thus having the ability to decrease fruit production by having fewer bisexual flowers, and more male-only flowers, that can pollinate but not set fruit, when resources are lean. Passionflower has the added bonus of being able to spread vegetatively through its bountiful runners, and thus skip or reduce the more expensive sexual reproduction when appropriate. I bet many humans wish they had this kind of reproductive flexibility!

Edible Fruit

Passionflower is also called maypop, the origin of the name is often attributed to children’s proclivity for jumping on the hollow fruits for the simple joy of hearing them “pop”. Daniel Austin demystifies this common etymological misconception in Florida Ethnobotany: “The names maricock and maracocks gave rise to maracoc, maycock, maypop (Alabama, North Carolina), mollypop (Alabama, North Carolina) ……All of these names are supposedly derived from mahcawq (Powhatan), akin to machkak (Menomini)…”[ii]

Immature fruit of passionflower

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The ripe fruits have a spongy partition, interesting in texture, which bears the ripe whitish yellow edible flesh surrounding the black hard seeds. I pop open the fruits when they are starting to turn yellow and begin to wrinkle, and slurp up the seedy flesh. I prefer to chew up the crunchy edible seeds, but some folks opt to spit them out. The fruit has been eaten and perhaps cultivated by Native Americans as evidenced by historical accounts and the presence of seeds in many archeological sites. One historical account from 1612 stated, “… yt is a good Sommer Cooling fruict, and in every field where the indigenous people plant their Corne be Cart-loades of them.” [iii]

It is likely that Native people encouraged this native weedy vine in their corn/bean/squash patches typical of traditional polyculture farming methods (growing different species of plants together, and allowing/encouraging weedy edibles to fill in bare patches).

Passiflora incarnata edible fruit (not quite ripe for eating)

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The taste is sour/sweet, with the unripe fruits being decidedly sourer. The passion fruit of commerce is the closely related Passiflora edulis, native to South America, now grown throughout the tropics for its tasty fresh fruit and juice.

Medicinal Uses

Common Name: Passionflower, maypop, old field apricot

Scientific name:

• Passiflora incarnata – official species. Native vine to the southeastern US, growing west to eastern Texas and Oklahoma, and north to southern Illinois, Ohio and Pennsylvania. Passionflower grows south throughout all of Florida.

Distribution of species by US County/State Note: caution using other Passionflower species, as not all have been used traditionally and some may be toxic.

Family: Passifloraceae

Cultivated/Wildcrafted: Passionflower is abundant throughout an extensive range, so it’s not under threat as a species. Although, in the peripheries of its range, it may be only sporadically found. At the time of this writing, most of the major herbal distributors in the U.S. are selling organically grown herb from Italy, which is surprising considering its abundance and ease of cultivation in the southeastern U.S.

Part used:  Leaves, stem, and flowers, harvest when the leaves are green and vital

Preparation & Dosage:               

Tincture: 1:2 95% fresh herb

1:5 50 % freshly dried herb

Both preparations: 2-4 droppers full up to three times/day

Tea: .5 to 2 grams of herb per cup of water as an infusion up to 3  times/day

Passionflower vine

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Actions:

• hypnotic (sleep-aid)
• analgesic (pain-reliever)
• hypotensive (lowers blood pressure)
• nervine
• anxiolytic (anti-anxiety)
• anti-spasmodic
• antidepressant

Energetics: slightly cooling and drying, mildly bitter

Traditional Uses: The Cherokee use the roots as a poultice to draw out inflammation in thorn wounds; tea of the root in the ear for earache; and tea of the root to wean infants. [iv] The Houma people infuse the roots as a blood tonic. ⁱⁱ    

It is interesting to note that contemporary herbalists use primarily the leaves, stems and flowers, whereas the ethnobotanical literature cites medicinal use of the roots only. In discussing its inclusion into the Eclectic material medica, Felter and Lloyd state in King’s American Dispensatory: [v]

Passiflora was introduced into medicine in 1839 or 1840 by Dr. L. Phares, of Mississippi, who, in the New Orleans Medical Journal, records some trials of the drug made by Dr. W. B. Lindsay, of Bayou Gros Tete, La. The use of the remedy has been revived within recent years, Prof. I. J. M. Goss, M. D., of Georgia, having introduced it into Eclectic practice. Prof. Goss, who introduced it to the Eclectic profession, employed the root and its preparations. We know of physicians who prefer the tincture of the leaves, and others still, who desire the root with a few inches of the stem attached.

Indications/Usages:[vi] [vii]

Nervous system/antispasmodic: insomnia, anxiety, anxietous depression, hypersensitivity to pain, headaches, agitation, transitioning from addictions, tics, hiccoughs, overstimulation, nervine tonic in preventing outbreaks of the herpes simplex virus, stress-induced hypertension, and menstrual cramps. The mandala-like flower demonstrates the powerful signature of its use in circular thinking, especially during insomnia; passionflower is especially suited for folks who have a hard time letting things go, mulling them over incessantly in a repetitive manner.

Children: insomnia; trouble sleeping through the night; teething; colic; adjunct treatment in asthma; especially with panic around asthma attacks; whooping cough.  See the notes below on calculating dosages for children.

Pregnancy: [viii] [ix] headache and pain, in general; prevention of herpes outbreak; hypertension; help with insomnia and exhaustion in postpartum depression; insomnia and anxiety. Please see the notes in the contra-indications section regarding passionflower’s safety in pregnancy.

Eclectic specific indications and uses: [v] irritation of brain and nervous system with atony; sleeplessness from overwork, worry, or from febrile excitement, and in the young and aged; neuralgic pains with debility; exhaustion from cerebral fullness, or from excitement; convulsive movements; infantile nervous irritation; nervous headache; tetanus; hysteria; oppressed breathing; cardiac palpitation from excitement or shock.

Michael Moorisms: [x] Cardiovascular excess in mesomorphs, sthenic middle-aged women; complementary with Crataegus, lowers diastolic pressure; PMS depression, PMS with insomnia; insomnia in sthenic individuals; and headache in hypertensive states with tinnitus.

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Personal experience: I use passionflower, primarily in tincture form, for insomnia, especially with circular thinking. The person is lying in bed mulling over an unpleasant situation in their life or something they said that day, and they just can’t let it go. It is beneficial in both sleep onset and sleep maintenance insomnia. I often combine it with valerian and/or skullcap, and less frequently, hops.

Passionflower is one of the herbs I use commonly for dysmenorrhea (menstrual cramps), often in combination with motherwort, black cohosh, and kava kava. Many people find relief with passionflower for cranky PMS moments.

Considered safe for children, it is beneficial internally to take the edge off teething, and to help children relax when they are climbing up the walls. Many parents use it to help children who wake frequently throughout the night sleep more soundly. As one of our safer anti-anxiety herbs, it can be helpful in treating children’s acute or chronic anxiety, and also to help them deal with an acutely traumatic or stressful situation.

Passionflower is one of my favored remedies for acute musculoskeletal pain; I use it in combination with meadowsweet, black birch, and skullcap for muscle strains, sprains and joint inflammation in general.

Passionflower medicine

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Contraindications/ Side effects: [x] bradycardia; hypotension; concurrent use of pharmaceutical sedatives.

According to Mills and Bone[xi], passionflower is in the following category of herbs:

Drugs that have been taken by only a limited number of pregnant women and women of childbearing age*, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have not shown evidence of an increased occurrence of fetal damage.

*Chestnut Note: Not all pregnant people are women.

In the American Herbal Products Association Botanical Safety Book[xii], Passionflower is not contra-indicated in pregnancy or lactation.

In Herbal Medicines, third edition {vi}, Barnes et al report no recorded drug/herb interactions, however a hydroalcoholic extract was reported to potentiate rhythmic rat spasms in isolated rat uterus, and based on these results, the author’s caution against using passionflower in pregnancy.

I am particularly conservative with herbal use in pregnancy, and believe that herbs should only been used when necessary and when there is a strong historical precedence. It is difficult to extrapolate from the ethnobotanical literature on passionflower’s use during pregnancy since little has been recorded on the herbs usage in general; contemporary use of the herb does not seem to match the recorded uses. That said, many contemporary herbalists and midwives recommend the herb’s use in pregnancy, and it is generally considered safe by most sources on botanical medicine safety. In addition, there are no adverse pregnancy events reported.

I also think intuition is a valuable tool in determining whether on not to use an herb in any situation (in combination with expert advice and research). Trust your body and trust your instincts if they tell you not to take an herb!

Determining dosage in children by weight:

To determine the child’s dosage by weight, you can assume that the adult dosage is for a 150-pound adult. Divide the child’s weight by 150. Take that number and multiply it by the recommended adult dosage. For example, if your child weighs 50 pounds, they will need one-third the recommended dose for a 150-pound adult. If the adult dosage is three droppers full of a tincture, they will need one third of that dose, which is one dropper full (1/3 of 3 droppers full). A 25-pound child would need one-sixth the adult dose, so they would receive one half of a dropper full (1/6 of 3 droppers full).