The ghost orchid is aptly named for a few reasons. Its white flowers have a vaguely spectral appearance, and they seem to hover in the forest due to an illusion created by the leafless plant. This effect also makes the rare orchid even harder to find, especially outside the brief, unpredictable window when it blooms in summer.
Unfortunately, the ghost orchid is also at risk of living up to its name in another way. It's an endangered species, limited to scattered populations in Cuba, the Bahamas and Florida, where it exists in just three southwestern counties. It inhabits remote swamp forests and small wooded islands, yet still faces an array of threats from humans, namely poaching, climate change, loss of pollinators and loss of habitat.
The species has long enchanted anyone lucky enough to see it, and we're still learning its secrets — including new research that challenges what we thought we knew about its pollinators. In honor of the ghost orchid's haunting mystique, and of scientists' quest to save it, here's a closer look at this unique floral phantom:
1. It only blooms once a year for a few weeks — or not at all.
The ghost orchid (Dendrophylax lindenii) blooms between June and August, typically just once per year for a period of about one or two weeks. Or it might just take the year off. As few as 10% of ghost orchids may bloom in a given year, and of those, as few as 10% may be pollinated.
2. It has scales instead of leaves.
The ghost orchid is what's known as a "leafless" orchid, since its leaves have been reduced to scales and mature plants seem to lack foliage. It also has a reduced stem, which is often hard to see even if you somehow find a ghost orchid in the wild.
3. It's mostly made of roots.
In lieu of leaves and a stem, the ghost orchid plant consists mostly of roots, which grow on a tree's bark without need for the soil below. That's because the ghost orchid is an epiphyte, a term for plants that grow not in soil, but on trees and other hosts sort of like a parasite. Unlike parasites, epiphytes don't take nutrients from their hosts and don't necessarily cause any trouble for them. It tends to grow on the main trunk or large boughs of a living tree, often several feet off the ground, although it can be located much higher up in the canopy.
4. Its roots act like leaves.
The ghost orchid may not have leaves to speak of, but that doesn't mean it has given up on photosynthesis. Although its roots already have their hands full — they anchor the orchid onto its tree, while also taking in water and nutrients — they fill this role, too. The roots contain the chlorophyll needed for photosynthesis, rendering leaves unnecessary. The roots also feature small white marks known as pneumatodes, which perform the gas exchange needed for respiration and photosynthesis.
When the orchid isn't in bloom, the mass of roots look like "unremarkable bits of green linguine," as National Geographic's Douglas Main recently described them.
5. Its flowers look like they're floating in the forest.
An endangered ghost orchid blooms at the Florida Panther National Wildlife Refuge. (Photo: Josh O'Connor [CC BY 2.0, public domain]/U.S. Fish and Wildlife Service/Flickr)
The greenish roots blend in with the bark of trees where ghost orchids grow, making them well-camouflaged when they aren't blooming, especially in the dimly lit understory. During the brief window when they do bloom, the flower grows on a thin spike extending outward from the roots. The roots act like a puppeteer dressed to match the background, dangling the flower as if it's floating freely in the forest.
Although ghost orchid is undoubtedly its coolest name, the plant is also known as "palm polly" or the "white frog orchid," a reference to the pair of long, lateral tendrils from its lower petal that vaguely resemble the hind legs of a frog.
6. It smells kind of like apples, especially in the morning.
The ghost orchid scent comes from several compounds, especially (E,E)-α-Farnesene, which is also found in the skin of apples and other fruits. (Photo: Doug Goldman, hosted by the USDA-NRCS PLANTS Database)
At an undisclosed location in South Florida, about 13 ghost orchids abruptly bloomed in the summer of 2009, giving scientists a unique opportunity to study the species in the wild. That included a team of researchers who investigated the orchid's "floral headspace," using gas chromatography-mass spectrometry (GC-MS) to identify volatile compounds in the flower's scent.
They identified several organic chemicals known as terpenoids, the most abundant of which was (E,E)-α-farnesene, a compound found in the natural coating of apples, pears and other fruits. It accounted for 71% of the ghost orchid's blend of fragrant compounds, followed by (E)-β-ocimene (9%), methyl salicylate (8%), linalool (5%), sabinene (4%), (E)-α-bergamotene (2%), α-pinene (1%) and 3-carene (1%).
From about 5 centimeters (2 inches) away, "the floral scent of D. lindenii was readily detectable to the authors," they reported in the European Journal of Environmental Sciences, "and seemed to intensify at sunset." The fragrance was most potent in the early morning, they added, between 1 and 6 a.m. local time. "The scent can best be described as sweet-smelling and somewhat fruity," they wrote.
7. It was long thought to rely on just one moth for pollination.
The giant sphinx moth (Cocytius antaeus) with its tongue extended. (Photo: Politikaner [CC BY-SA 3.0]/Wikimedia Commons)
The ghost orchid's pollen is hidden deep within its flowers, and so it can only be pollinated by an insect with a proboscis long enough to reach all the way inside. This is similar to the famous Darwin's orchid of Madagascar, named after naturalist Charles Darwin's 1862 declaration that its long flower must be pollinated by an unknown moth with an unusually long tongue. Years after Darwin's death, the Morgan's sphinx moth was revealed to be the orchid's specialist pollinator.
For ghost orchids, the long-tongued pollinator was long ago identified as the giant sphinx moth, which is native to South and Central America but relatively rare in North America, with only occasional sightings in Florida and a few other southern U.S. states. It's widely described as the sole pollinator of ghost orchids, thanks to its long proboscis and a lack of evidence for any other pollinators. Its larvae feed on the pond apple tree, which is also an important host for ghost orchids.
8. Its pollination might not be as simple as we thought.
The fig sphinx moth (Pachylia ficus), pictured here on Grand Cayman island, seems to be an overlooked pollinator of ghost orchids. (Photo: Charles J. Sharp [CC BY-SA 4.0]/Wikimedia Commons)
Despite conventional wisdom about the ghost orchid's reliance on giant sphinx moths, newly released photos taken in Florida suggest the reality is more complicated. Wildlife photographer Carlton Ward Jr. recently set up a camera trap in Florida Panther National Wildlife Refuge, located just northwest of Big Cypress National Preserve, and caught images of five different moth species visiting ghost orchids. As National Geographic reports, two of these moths — the fig sphinx and pawpaw sphinx — had ghost orchid pollen on their heads.
This was later backed up by another photographer, Mac Stone, who captured images of a fig sphinx moth visiting a ghost orchid with the plant's pollen on its head. Both photographers also got photos of giant sphinx moths visiting ghost orchids, but none were carrying ghost-orchid pollen, raising the possibility that giant sphinx tongues are long enough to "steal" nectar from ghost orchids without actually pollinating them.
These findings have been submitted to a peer-reviewed journal but not yet published, according to National Geographic. If the ghost orchid really does have multiple pollinators — with or without the giant sphinx — it would be welcome news, since it would mean the orchid's reproduction doesn't depend entirely on one rare insect. "It's good to have redundancy in ecosystems," Mike Owen, a biologist at Fakahatchee Strand Preserve State Park, tells the magazine. And that may be especially valuable now, given the threat of pesticides and other factors fueling the widespread decline of insects around the world, including many important pollinators.
9. Its habitats are becoming more hazardous.
Fakahatchee Strand Preserve State Park is a haven for ghost orchids in South Florida, but it's vulnerable to sea-level rise, hurricanes and other threats amplified by climate change. (Photo: Danita Delmont/Shutterstock)
In Florida, ghost orchids tend to grow on just three tree species — pop ash, pond apple and bald cypress — but in Cuba they've been found growing on at least 18 different host trees. "Although populations of D. lindenii in southern Florida and Cuba are separated by only 600 km, this species appears to occupy two different habitats and colonizes a different set of host trees," researchers noted in a 2018 study. Ghost orchids in Florida also grow slightly higher off the ground than in Cuba, the authors noted, possibly because stagnant water prevents seedlings from growing on submerged tree surfaces during South Florida's rainy season.
In both countries, however, the ghost orchid's habitats "are undergoing rapid, irreversible change imposed by climate change and other factors," the researchers added. "Both regions, for example, are vulnerable to sea-level rise this century given their low elevation, and the severity and frequency of tropical cyclone activity is another concern." Ghost orchids have already experienced a steady decline in the wild, and based on simulations of habitat changes, "hurricanes and similar disturbances could result in near certain extinction in short time horizons," researchers reported in 2015, possibly within a period of 25 years.
Yet another threat comes from the emerald ash borer, an invasive insect that kills ash trees. It hasn't reached Florida yet, but if it infects mature stands of pop ash trees in places like Florida Panther National Wildlife Refuge — where 69% of all ghost orchids grow on pop ash — it could have a devastating effect on the species.
10. It has a problem with poachers, too.
Along with its general rarity and remote, inhospitable habitat, the ghost orchid's camouflage makes it incredibly hard to find in the wild. That doesn't stop some people from trying, though, and not always for good reasons.
An estimated 2,000 ghost orchids live in the wild across South Florida, according to the University of Florida Institute of Food and Agricultural Sciences (IFAS), although a recent survey suggests there might be more. And while researchers want to know where those orchids are, the locations are often kept secret due to the threat of poachers, who may be willing to risk their lives in search of wild ghost orchids.
Although the rare plants may command a high price on the black market, this is stupid even beyond the obvious legal, ethical and ecological reasons. Ghost orchids rarely survive removal from the wild. "People who manage to remove an orchid from its environment are usually disappointed because ghost orchid plants almost always die in captivity," points out Gardening Know How.
11. It brought together Meryl Streep and Nicolas Cage.
In December 1993, horticulturalist John Laroche and three other men were arrested for trying to steal 136 plants from Fakahatchee Strand Preserve State Park. Among their haul were dozens of wild orchids, including several specimens of ghost orchid, which Laroche reportedly hoped to clone and sell for a profit. This case was covered for The New Yorker in 1995 by journalist Susan Orlean, who later adapted her coverage into the 1998 nonfiction book "The Orchid Thief."
Orlean's book was then adapted by screenwriter Charlie Kaufman for the 2002 film "Adaptation," directed by Spike Jonze. Among other notable quirks of the movie, which partly fictionalizes the story, it features the odd pairing of Meryl Streep, who played Orlean, with Nicolas Cage, who played Kaufman as well as his fictional twin brother. (Chris Cooper, who played Laroche, won an Academy Award for his role.)
12. It's very hard to cultivate, but one fungus seems to help.
Ghost orchids have very particular growing requirements, including high temperatures, high humidity, diffuse light, specific kinds of trees and a specific symbiotic fungus. (Photo: Rhona Wise/AFP/Getty Images)
The ghost orchid not only tends to die when removed from its natural habitat, but it's also famously ill-suited to captivity in general. Botanists long struggled to cultivate the orchid, hoping to create a population of captive-bred plants that could be periodically transplanted to help buffer their wild counterparts.
Although the ghost orchid has seemed impossible to cultivate, researchers have made some breakthroughs in recent years. Michael Kane, a professor of environmental horticulture at the University of Florida, has been working with a team of researchers to bring ghost orchid seeds from the wild to a propagation lab, where they try to germinate the seeds under sterile conditions on a gelled medium and then transfer the plants into a greenhouse.
The key is not only recreating precise conditions that ghost orchids need to thrive, but also providing them with the right fungus. Ghost orchid seeds won't germinate unless they're infected with a specific mycorrhizal fungus, which provides energy for the germination and then grows on the plant's roots as part of a symbiotic relationship. In the wild, ghost orchids seem to colonize trees with moist, corrugated bark that harbors fungi in the genus Ceratobasidium, and researchers have identified certain fungal strains that lead to higher germination rates.
Michael Kane, environmental horticulturist at the University of Florida, attaches an endangered ghost orchid to a host tree at the Florida Panther National Wildlife Refuge in 2016. (Photo: Rhona Wise/AFP/Getty Images)
Kane and his team have been so successful in cultivating ghost orchids that they've also begun reintroducing them to the wild. The researchers planted 80 orchids in the wild in 2015, achieving an 80% survival rate a year later, then followed up with 160 more orchids in 2016. This alone may not save the species, especially if its habitats remain in danger, but it's still a big step toward preserving these incredible ghosts.
"For orchid conservation, this is big," Kane said in 2016. "We are very excited."