Corkystem passionflower (Passiflora suberosa L.) is a mainstay of my butterfly garden. I just wish it would grow where I want it instead of collaborating with the birds to migrate to places where it is a pest. So far it has resisted my attempts to train it up a trellis or fence, yet it scrambles exuberantly in, around, through, and over shrubs and trees. If it has nowhere to climb, it spreads happily over the ground, especially where I have planted native heliotropium (Heliotropium polyphyllum). I could leave it as a ground cover, but since it is a vine, it presents a tripping hazard. I have a lot of digging out and potting up ahead, because I need to save at least some of the volunteers.
The genus Passiflora is the larval host for the zebra longwing, julia longwing, and much under-appreciated Gulf fritillary. The striking, orange Julias are uncommon in our garden. They tend to show up in a bunch and then disappear for years. We sometimes get zebra longwings, but they really prefer a shadier habitat than our yard offers. Zebra longwings roost in long chains at night, and the sight of such chains is absolutely breathtaking. The zebra longwing is Florida's state butterfly.
 Gulf Fritillary Caterpillars on Passiflora suberosa |
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Zebra Longwing Caterpillar Unripe Passiflora berries Collier-Seminole State Park |
The beauty of a Gulf fritillary is hard to capture in paint or with my very basic camera equipment. A newly-emerged adult gleams bright copper-orange, like the proberbial new penny. The undersides of the wings have a pattern of iridiscent silvery patches which reflect light spectacularly and brilliantly.
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The scanner cannot capture the silvery flash of the underwings. These are dead individuals I have collected from the yard. |
Passiflora suberosa is one of 7 species of passionflower native to Florida, but the purple passionflower, P. incarnata, is the only other one which occurs naturally in this area. Several exotic species, like the flamboyant scarlet passionflower ( P. coccinea) also flourish in the state. P. incarnata is a large vine, has a showy purple flower, and will get devoured by caterpillars. It dies back during our dry season.
"Maypop" is another common name for P. incarnata. When I was a child we lived in South Carolina with my grandparents and unmarried aunt while my father served in the Korean War. I tagged along with my Aunt Iola, whom I called "Ant Ola." (I still pronounce "aunt" as "ant").
Even though I was afraid of the cows, who seemed awfully big, I liked accompanying my aunt when she took them out to pasture every morning. What I later realized was P. incarnata grew wildly in one spot. I asked her what they were, and she replied, "Maypops." When I asked her why, her answer was, "because they may pop and they may not." It is fascinating how certain little things can be preserved so vividly in our memories.
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Zebra Longwing Heliconius charitonius Delnor-Wiggins Pass State Park |
Corkystemmed passionflower is much more diminutive, and far less showy than its purple and red cousins. I agree with Rufino Osorio, who writes that while it first seems to have no obvious horticultural appeal, it's merits show themselves over time. The vine begins tender and green, and gradually adds ridges of corky material until it is enclosed completely. Near the roots of an undisturbed vine the stem can reach a diameter of an inch or more, and certainly presents an interesting texture.
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| Passiflora suberosa Notice Corky Stem |
The leaves have longish petioles and alternate around the stem. The surfaces are smooth, and the color varies from a yellowish green in bright sun to a more intense green in shade. The petioles have 2 raised "dots" opposite each other close to the base of the leaf. These are extrafloral nectaries. The plant often displays "heterophylly," a fancy term for having leaves of different shapes. They can be simple and entire, or partially or deeply lobed. The presence of heterophylly in the plants in our yard varies, probably depending on what has been pollinated. Roger Hammer writes that lepidopterists surmise that the varying shape is a means to fool the butterflies so they don't lay as many eggs on the plant. The vine climbs and clings by tendrils emerging at the base of the leaves.
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| Heterophylly in Passiflora suberosa |
The flower is small and delicate, about one-half to three-quarters inch in diameter. What look like petals, but really are sepals, are white or pale spring green. Pollinators of various sorts like them, because they produce a lot of berries throughout the year. The fruits start out green, turn blue, and then blue-black when ripe. Sometimes they have a chalky "bloom" like blueberries. They are roughly spherical and about a quarter-inch in diameter - about the size of a Spanish caper. They don't taste bad, but contain so many tiny seeds that they are mostly grit. Better leave them for the birds.
That brings us back to my struggle to keep the vine from eating the garden. The place it thrives most vigorously is all through and over a clump of bougainvilleas. The bougainvillea's vicious thorns and dense growth prevent me from getting at the passionvines' roots, and even if I did, the mockingbirds would reseed them promptly. They effectively cultivate the vine because they poop as they forage for the berries. The bougainvilleas aren't native, but they don't consume any resources beyond space and rainwater. The tiny white flowers nestled in the plant's hot-magenta-pink bracts attract a fair number of small pollinators, and the mess of bougainvillea branches and passiflora vines provides a prime nesting site for the mockingbirds. They have reared several successful broods there over the last few years.
So it's a standoff. I can't beat it, so I settle for beating it back when it threatens, kudzu-like, to suffocate the other plants. And I do like the butterflies.
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Gulf Fritillary Agraulis vanillae Nectaring on Blue Porterweed, Our Garden |
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