A Bat-Pollinated Passion Flower From Ecuador

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Say "hello" to one of Passiflora's most recent additions, the bat-pollinated Passiflora unipetala. The first specimens of this vine were discovered back in 2009 by Nathan Muchhala while studying flower visiting bats in northern Ecuador. It is a peculiar member of the genus to say the least. 

One of the most remarkable features of this plant are its flowers. Unlike its multi-petaled cousins, this species stands out in producing a single large petal, which is unique for not only the genus, but the whole family as well. The petal is quite large and resembles a bright yellow roof covering the anthers and stigma. At the base of the flower sits the nectar chamber. The body of the plant consists of a vine that has been observed to grow upwards of 6 meters up into the canopy.

Flowering in this species occurs at night. Their large size, irregular funnel shape, and bright yellow coloring all point to a pollination syndrome with bats. Indeed, pollen of this species has been found on the fur of at least three different bat species. Multiple observations (pictured here) of bats visiting the flowers helped to confirm. Oddly enough for a bat-pollinated plant, the flowers produce no detectable odor whatsoever. However, another aspect of its unique floral morphology is worth noting. 

The surface of the flower has an undulating appearance. Also, the sepals themselves have lots of folds and indentations, including lots of dish-shaped pockets. It is thought that these might help the flower support the weight of visiting bats. They may also have special acoustic properties that help the bats locate the flowers via echolocation. Though this must be tested before we can say for sure, other plants have converged on a similar strategy (read here and here).

As it stands currently, Passiflora unipetala is endemic to only a couple high elevation cloud forests in northern Ecuador. It has only ever been found at two locations and sadly a landslide wiped out the type specimen from which the species description was made. As such, its introduction to the world came complete with a spot on the IUCN Redlist as critically endangered. Luckily, the two localities in which this species has been found are located on privately protected properties. Let's just hope more populations are discovered in the not-too-distant future.

Photo Credits: [1] 

Further Reading: [1]

A Unique Passionflower Endemic to Costa Rica

I love small flowers, especially if they pack in a lot of detail. That's is why this passion flower caught my eye. Meet Passiflora boenderi, a charismatic vine endemic to a small region of Costa Rica. Apparently this species had been sitting around in herbaria for years under a different name. It wasn't until living specimens were observed that botanists realized it is a distinct species.

There is a lot to look at on this species. The flowers themselves are some of the smallest in the genus. They pack in all of the detail of a larger passion flower, just in miniature. The leaves are quite stunning as well. They're bilobed with a tinge of purple and covered in bright, orange-yellow spots. The spots themselves serve an important role in protecting this plant from herbivores.

The genus Passiflora is part of an intense evolutionary arms race with a genus of butterfly known as Heliconius. Their caterpillars feed on the foliage of passion flowers. As such, Passiflora have evolved a variety of means that help them to avoid the attention of gravid female butterflies. The orange spots on the leaves of P. boenderi are one such adaptation and they serve a dual function.

The first is a visual deterrent. Female Heliconius prefer to lay their eggs on caterpillar-free leaves. This makes sense. Why bother laying eggs where there will be ample competition for food. The spots mimic, both in size and shape, the appearance of Heliconius eggs. A female looking for a spot to lay will see these spots and move on to another plant. In addition to the visual mimicry, these spots also secrete nectar. The energy-rich nectar inevitably attracts ants, which viciously defend them as a food source. If a caterpillar (or any other herbivore fore that matter) were to start munching on the leaves, the ants quickly drive them off.

Because of its limited range, P. boebderi is under threat of extinction. Habitat destruction of its lowland habitat for palm oil, pineapples, and vacation resorts is an ongoing threat to the long term survival of this species and many others. I was fortunate enough to have encountered this plant growing in the Cliamtron at the Missouri Botanical Garden but I fear that if we keep on doing what we humans are so good at, botanical gardens may be the only place this species will be found growing in the not too distant future.

Further Reading: [1] [2]