Post by Jen B
Many years ago, while hiking through a prairie at dusk, I saw a stalk of delicate white flowers. They seemed to rise and hover above the surrounding plants like a group of little dancing ghosts. This was the first and last time I ever saw an eastern prairie fringed orchid (Platanthera leucophaea). Due to its dwindling numbers and hidden habitats, this rare plant has reached almost mythical status—a holy grail of sorts in the Midwest. We’re thrilled that this endangered native orchid seems to be gaining a foothold in the Lake County Forest Preserves, which are home to some of the largest remaining populations. Just this month, one of our restoration ecologists discovered an orchid in bloom (photo below). It was found at one of the preserves known to provide habitat for this species but is the first documentation of a population at the site.
Adding difficulty to the search for this orchid is its idiosyncratic life cycle. The number of individuals in a population varies greatly from year to year with some years producing record numbers of flowering orchids and other years seeing few to none. Seed germination is reliant on a special relationship between the roots of the orchid and a soil fungus. This fungus provides nutrients to a seedling that can remain underground for years until conditions are just right. Eastern prairie fringed orchids can live in a variety of habitats from wetlands to prairies, yet they require full sunlight and little competition from surrounding vegetation to thrive. Research has shown that high precipitation levels and fire are two factors that promote flowering of these unique orchids. Blooms typically only last one week to 10 days.
Eastern prairie fringed orchids have a jasmine-like fragrance that intensifies as night falls. The perfumed prairie air attracts this orchid’s pollination soulmate—night flying hawkmoths (a.k.a Sphinx moths, family Sphingidae). Each flower’s large lower petal has three fringed parts and a nectar spur. The spur is one to two inches long, tube-like and holds a sweet treasure for these nocturnal creatures with a perfectly match proboscis. When a hawkmoth inserts its proboscis for a sip of nectar, the orchid’s pollen sticks to it in a small bundle. The pollen is then transferred to the next orchid the moth visits.
Illinois historically contained the most extensive populations of eastern prairie fringed orchids. In 1927, botanist Herman Pepoon described the orchids as “a blanket of white on the moist, low prairie.” The threads of this “blanket” quickly unraveled due to many factors, including habitat loss, competition from non-native invasive plants, and over-collection by humans. The orchid’s dependence on just a few hawkmoth pollinators, which are vulnerable to habitat loss and pesticide use, has contributed to its disappearance as well.
To prevent this endangered orchid from becoming extinct, the U.S. Fish and Wildlife Service, land management agencies, research institutions and volunteer stewards have rallied to protect remaining populations. To protect the eastern prairie fringed orchid the Lake County Forest Preserves and dedicated volunteers:
- Conduct an annual census of plants.
- Control competing exotic plants.
- Induce seed production through hand pollination.
- Collect seed capsules.
- Disperse seeds at sites deemed suitable for reintroduction.
Our monitoring and hand pollination efforts help ensure the viability of this extremely rare orchid species in hopes that it will not disappear entirely and become a true ghost of the prairie.