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Hand Pollination Used for Rare Orchid When There’s a Lack of Pollinators

June 18, 2019 12:00 AM
By: Kristi Allen, Pennsylvania Plant Conservation Network Program Coordinator

Hand Pollination Used for Rare Orchid When There’s a Lack of Pollinators

​Plants need pollinators -- bees, butterflies, moths, bats -- to help them reproduce. In the case of one rare orchid in Pennsylvania, it’s people who are helping to perform this important task.

On a beautiful late spring day, I was lucky enough to join DCNR Bureau of Forestry Botanist Kelly Sitch, Pennsylvania Natural Heritage Program Botanist John Kunsman, and Larry Klotz from Shippensburg University, out in the field to survey the rare Arethusa bulbosa -- commonly known as “Dragon’s Mouth orchid.”

Kelly has been working with this charismatic plant since 2011. He told me that the trek out to monitor these orchids is his favorite part of field season because the plant is so elusive -- there’s so much that we don’t yet know about this plant; and, every year, it seems like we’re discovering a little bit more.

Every year, he tries to bring a new person along because they seem to have beginner’s luck -- always seeming to discover a new population that previously hadn’t been identified.

As we venture into the woods, I cross my fingers that I will continue the streak of good luck.

We bushwhacked along creek beds and through dense mountain laurel. At times, we were almost on all fours to get through the compact vegetation.

Eventually, we emerged into an herbaceous opening -- soft, wet sphagnum moss under our feet, red maple and hemlock providing a shady respite from the sun -- though we should have been grateful to see the sun; it seems like it’s been raining for weeks.

Dragon’s Mouth Orchid Imperiled in Pennsylvania

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Our goal was to monitor the population -- Dragon’s Mouth orchid is critically imperiled in our state, with just a few populations remaining.

Collection, deer browsing, and habitat destruction have contributed to the decline of this beautiful orchid. Its elusive pollination habits also have prevented this plant from thriving.

It’s suspected that the orchid is pollinated by a species of bumblebee, and indeed, we did see a lone bee, buzzing through the forest near a patch of orchids. But it didn’t seem to be interested in the magenta-pink blooms.

In recent years, it has become customary to be joined by plant researcher, Dr. Peter Zale, the Associate Director of Conservation, Plant Breeding, and Collections at Longwood Gardens. 

Even though the flowers are attractive and fragrant, they offer little to no nectar reward to the pollinator.

Luckily, Peter doesn’t need a nectar reward to pollinate the orchid –- his reward comes from researching best practices in orchid propagation.

While the rest of the team searched for and counted the number of individual plants, Dr. Zale hand pollinated a small number of flowers.

Hand Pollination Used More for Rare Plants

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Dr. Peter Zale hand pollinating Dragon's Mouth orchid.

Hand pollination is done by manually transferring pollen from the stamen of one plant to the pistil of another.

It’s useful when there is a lack of pollinators -- a problem that the Arethusa seems to be facing.

“Hand pollination of those plants has been the only reliable way to ensure seed set in these populations, and it is a management technique we are using more and more,” Peter said.

“Even in the event that we don’t need seeds for ex situ propagation experiments, hand pollination appears to be a necessary management tool to make sure seeds are dispersed in situ to promote seed bank development and seedling recruitment.”

Since active management of the Dragon’s Mouth orchid began back in 2011, the number of flowering and vegetative plants has steadily increased, giving hope that the plant is reproducing more successfully.

Research Efforts on Dragon’s Mouth Continue

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Dr. Peter Zale dissecting immature Dragon's Mouth orchid.

Dr. Zale has been hand pollinating and experimenting with propagation since 2016.

Until we know more about the reproductive viability of this plant, we’ll continue to hand pollinate and focus on ex situ conservation efforts.

It is hoped that genetically similar plants that have grown up at Longwood Gardens will eventually be out planted with their parent population.

Pennsylvania Plant Conservation Network

Work with outside partners and stakeholders on the conservation of endangered plants in Pennsylvania is one of the goals of the Pennsylvania Plant Conservation Network.

The Pennsylvania Plant Conservation Network (PPCN) is a new program at DCNR that works collaboratively to promote and coordinate the conservation of native plant species through education, outreach, and stewardship.

If you’re interested in getting involved in learning more about rare native plants, please contact PPCN Program Coordinator, Kristi Allen.


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