PacSci Perspectives

Psiguria – The Little Vine That Butterflies Love To Pollinate

by | Jun 21, 2016

Horticulturist Jenn Purnell and her team have filled our Tropical Butterfly House with lush plants featuring showy foliage, big flowers, and towering size. But compared to many of the plantings, the Psiguria vine that grows up our emerging window is not too exciting. A guest might look at this plant and ask why we keep it. Staff and volunteers have sometimes accidentally cut its long, scrawny stem while cleaning up a flowerbed. Psiguria flowers are far between, and only a few are ever open. Why do we love this plant so much?

Don’t ask us. Ask the genus Heliconius (Longwing) butterflies that hang all over the sparse, Cheetos-orange blossoms. To them, Psiguria is the most beautiful thing in the greenhouse. What do they see in this plant (besides the outrageous color of the tiny flowers)?

Psiguria

To understand the attraction, it helps to know that Heliconius butterflies have an unusual ability for butterflies. They can digest pollen and use the proteins. All adult butterflies get food with a proboscis – a straw-like tube that can only drink liquids. But the Heliconius butterflies produce a fluid that can dissolve the protein in pollen granules and turn it into liquid form. They essentially use their saliva to turn pollen into a nutritious protein drink. Psiguia co-evolved with the Heliconius to meet the butterfly’s pollen needs, while the butterfly meets the plant’s pollination needs.

Psiguria

Each Psiguria flower is either male or female, with more male flowers produced. Their flowers can’t pollinate themselves. So the butterfly needs to visit at least a male and a female flower for seeds to form. Judging by all the little Psiguria fruit on our vine, this is definitely happening! Heliconius butterflies tend to sleep in large groups. As young butterflies join the population, they all fly out together to the Psiguria, teaching the younger members of the group where to find food.

Psiguria and two butterflies

The relationship between the plant and the butterfly is powerful enough that entomologists studying Heliconius in the wild will sometimes just station themselves near a Psiguria vine and wait for the butterflies to show up. You can watch this fruitful relationship by looking at the vine growing above the Emerging Window in our Tropical Butterfly House. Happy National Pollinator Week!

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