Purple Passionflower
Purple Passionflower, also known as Maypop or Passiflora incarnata, is a vigorous native vine that produces gorgeous flowers and edible fruit, and feeds the hungry-hungry caterpillars of vibrant Gulf Fritillary butterflies!
Gulf Fritillary caterpillars are quite striking, featuring intimidating but harmless black spikes on a bright orange background. They have big appetites, and sometimes a crop of caterpillars will eat ALL the leaves, but fortunately Purple Passionflower is well-adapted to defoliation and new leaves will grow fueled by energy stored in its root tissue.
I enjoy watching leaves in my garden being converted into butterflies via caterpillars!
We have a bumper crop of Purple Passionflower fruit in our James Island garden this year! The photos below show an unripe fruit (left and bottom right) as well as a ripe fruit (top right; harvested within a day of it falling onto the ground; still green on the outside).
Ripe passionfruit contain dozens of seeds, each surrounded by tangy-sweet juicy pulp in its own little pouch (aril). The seeds are crunchy but edible, so I usually use a spoon to scoop out the aril-encased seeds and eat both the pulp and the seeds. If you’d prefer the flavor without the crunch, you can separate the pulp from the seeds using a strainer.
Applied Botany: How does pollination lead to the production of fruit and seeds?
Eastern Carpenter Bees are the primary pollinators of Purple Passionflower, although multiple species of native bees as well as non-native honey bees visit the flowers to feed on nectar and gather pollen.
In July I enjoyed watching Eastern Carpenter Bees getting doused with pollen from downward-facing anthers while feeding on nectar at the center of the passionflower…
Departing the flower absolutely covered in pollen, flying to another flower, and then…
Transferring some of that pollen to one of the flower’s stigmas. Most flower pistils have 1 stigma at their tip to collect pollen (as shown in the diagram below), but passionflower has a branching pistil with 3 separate stigmas!
Next step: Individual grains of pollen germinate, each forming a pollen tube, eventually reaching an ovule within the flower's ovary and enabling fertilization!
Fertilized ovules develop into seeds, and each ripe passionfruit (which develops from the ovary) contains dozens of seeds, which means that many pollen grains must be successfully transferred from anthers to stigmas by these large fuzzy bees!
Where and how to plant?
In addition to growing vigorously, Purple Passionflower sends up suckers from underground runners, sometimes quite a distance from the original stem. So while this is definitely a garden-worthy vine, we advise putting careful thought into its planting location! Planting Purple Passionflower in a garden bed with well-mannered flowers and shrubs may lead to it completely overtaking the bed (unless you are ready and willing to prune frequently).
Good options for planting location include in a solo bed along a chain-link fence or at the base of a sturdy trellis surrounded by lawn (so that unwanted suckers can be controlled by mowing) or along a wild forest edge (so that the vines can climb trees and shrubs).
In terms of growing conditions, Purple Passionflower appreciates well-drained soil and 4+ hours of direct sun exposure.
I find that fruit production is higher in full-sun locations, especially if you pamper your vine by adding compost and a thick layer of pine straw mulch to the soil surface so that it doesn’t have to compete with grass or weeds for water or nutrients.
