NORTH CAROLINA PASSIFLORA SPECIES

NORTH CAROLINA PASSIFLORA SPECIES

 

Figure 1: Passiflora incarnata commonly called "Maypops" or Purple Passionflower.

 

Passiflora is a genus of approximately 513¹ species mostly found in the semi-tropics and of tropics Central and South America. Most species are vines, but shrubs, trees and herbaceous species also exist. The plants are grown extensively for their beautiful and unique flowers, edible fruits in some species, and foliage. Horticulturists have produced many hybrids and cultivars. According to Weakly ², North Carolina is home to two native Passiflora species, P. incarnata and P. lutea.

All Passiflora flowers have highly modified and unique flower morphology. Starting from the center of the flower there is a central column of tissue known as the androgynophore that elevates and supports both the male and female reproductive structures. In Passiflora incarnata this includes five anthers, a superior 3-locular ovary, and three large stigmas. Surrounding the base of the androgynophore is a ring of short filaments called the operculum. The operculum partially covers and hides floral nectaries encircling the androgynophore. Next is a corona made up of numerous thin filaments usually brightly colored. Then there are five petals and five sepals. Depending on the species, the sepals may or may not have awns on their tips. Lastly, some species may also have 3 glandular bracts on the peduncle ³ (Figure 1, 2, 3).

Figure 2: Side view of Passiflora incarnata showing the unusual flower morphology.

Figure 3: Notice the three glandular bracts on the peduncle being attended by ants.

Probably the best known of the two species in North Carolina is Passiflora incarnata more commonly known as Maypops, or Purple Passionflower (Figures 4). It is common across the state and is found in open disturbed areas such as old fields, pastures, fence rows, and roadsides. The large purple flowers bloom through-out the summer and into fall and produce both pollen and nectar. They are pollinated by various insects but primarily by carpenter bees (Figure 5, 6). The vine rambles across the surrounding vegetation and supports itself with tendrils. The alternate, deeply palmately 3-lobed leaves have serrated margins and the petioles have a pair of extra-floral nectaries (Figures 7,8,9). Late in the fall large green to yellowish egg-shaped fruits (berries) can be seen hanging from the vines (Figure 10). Supposedly, the popping noise made by stepping on these fruits is what gave rise to the common name ‘Maypops’. Passiflora incarnata and other Passiflora species are also critical host plants for various Lepidoptera especially, especially the Gulf Fritillary, Agraulis vanilla (Figures 11, 12, 13).

Figure 4: Top view of Passiflora incarnata flower.

Figure 5: Passiflora flowers produce both nectar and pollen that attracts a variety of pollinators.

Figure 6: Notice how the carpenter bee has to brush under the anther to reach the nectaries at the base of the androgynophore. 

Figure 7: Notice the alternate palmately lobed leaves with serrated margins.

Figure 8: Passiflora incarnata has extra-floral nectaries on the petioles.

Figure 9: A close-up of the extra-floral nectaries. Notice the ants feeding at the nectaries and the Gulf Fritillary, Agraulis vanillae larva.

Figure 10: Fruits of Passiflora incarnata, Purple Passionflower.

Figure 11: This was one of many Gulf Fritillary, Agraulis vanilla, larvae I observed feeding on my Passiflora vine this summer.

Figure 12: A Gulf Fritillary, Agraulis vanilla, larva forming its chrysalis.

Figure 13: An adult Gulf Fritillary, Agraulis vanilla.

Our second native Passiflora species is Yellow Passionflower, or Passiflora lutea.  Although this plant is also common and widely spread across the state it is not as well-known as Purple Passionflower. The smaller and less brightly colored flowers of P. lutea make it easy to overlook (Figures 14, 15, 16, 17). Yellow Passionflower is also a vine but unlike P. incarnata it can tolerate more shaded areas and is often found along wood margins, thickets, and in open forests. It also spreads vegetatively by long slender rhizomes. The leaves are shallowly palmately lobed (usually three lobes) with entire margins and the petioles lack nectary glands (Figure 18). The plants bloom late summer and into the fall and produces small dark blue-purple-black fruits (Figure 18, 19). 

Figure14: An illustration of Passiflora lutea. USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York. Vol. 2: 565.

Figure 15: Looking down onto a Passiflora lutea flower giving an especially nice view of the corona filaments. Photo by Doug Goldman, hosted by the USDA-NRCS PLANTS Database.

Figure 16: Another view of a Passiflora lutea, Yellow Passionflower flower.

Figure 17: A nice side view of a Yellow Passionflower flower showing the short filaments of the operculum around the elongated androgynophore. Notice the superior ovary underneath the spreading stigmas.

Figure 18: A nice view of the shallowly lobed leaf and an immature fruit from Passiflora lutea.

Figure 19: A mature fruit of Passiflora lutea. Photo by Doug Goldman, hosted by the USDA-NRCS PLANTS Database.

These two species are easily identified by flower color and size but there are other notable differences between Passiflora incarnata and P. lutea (Table 1).

Table 1: A summary of Passiflora incarnata and P. lutea characteristics ⁴. 

Passiflora incarnata Maypops	Passiflora lutea Yellow Passionflower
Vine with tendrils	Vine with tendrils
Alternate, palmately lobed and veined leaves, with serrated margins	Alternate, palmately lobed and veined leaves, with entire margins
Petioles have nectar glands	Petioles do not have nectar glands
Floral bracts present	Floral bracts absent
Sepals have awns	Sepals do not have awns
Petals purple	Petals pale green-yellow
Fruits green to yellowish	Fruits purple-black

The origin of the name ‘Passiflora’ is thought to have originated from early Spanish explorers and missionaries in the Americas. When they saw the unique morphology of Passiflora flowers it reminded them of Christ’s crucifixion. So ‘Passiflora’ or Passionflower, is derived from the Latin passio, for "suffering, enduring”, and Flora, for "goddess of flowers" ⁵ As a child growing up in the ‘Bible Belt’ I was taught the religious symbolism associated with Maypop flowers. The table below gives an example of how some people interpret the various plant parts with the crucifixion ⁶ (Table 2 ).

Table 2: Christian Symbolism of Passiflora Flowers

PLANT PART	REPRESENTS
Tendrils	Whips used to beat Christ before his crucifixion
Ovary	Hammer, or Holy Grail
3 Stigmas	Nails used to hang Christ form the cross
5 anthers	Wounds on Christ’s body
Coronal filaments	Crown of thorns placed upon Christ’s head
10 petals and sepals	The ten faithful apostles (minus Peter the denier and Judas the betrayer)
Purple color	The color of royalty, Christ the King
Red color	The blood of Christ

I hope you have enjoyed learning about our native Passiflora species. I encourage people to plant these wonderful vines because;

1.  they are beautiful and interesting plants/flowers,
2.  they provide nectar and pollen to native pollinators,
3.   they serve as host plants to a large variety of butterflies,
4.  and their fruits provide food to local animals and birds.

RESOURCES:

1. “The Plant List — A working list for all plant species.” Passiflora - The Plant List, www.theplantlist.org/1.1/browse/A/Passifloraceae/Passiflora/. 

2. Weakley, Alan S. Flora of the Southern and Mid-Atlantic States. Chapel Hill, NC: University of North Carolina Herbarium, North Carolina Botanical Garden, University of North Carolina, Chapel Hill, 2015. Print.

3. Magazine, Garden Design. “Botanic Notables: 500 Shades of Passiflora - Garden Design.” GardenDesign.com, Garden Design Magazine, 25 Feb. 2016, www.gardendesign.com/flowers/passion.html. 

4. Goldman, Douglas H., and John M. MacDougal. “Passiflora.” Flora of North America @ efloras.Org, www.efloras.org/flora_page.aspx?flora_id=1.

5. Graves, Julia. The Language of Plants: A Guide to the Doctrine of Signatures. Lindisfarne Books, 2012.

6. “Flora | Search Online Etymology Dictionary.” Index, www.etymonline.com/search?q=flora.

7. Unless otherwise noted, all photographs were taken by and are property of Tracie L. Jeffries.