HONOLULU — More than 30 years of research has led to a major victory in protecting one of Hawai‘i’s rarest plants — a native orchid of the Islands’ high forests and bogs that was down to fewer than 50 known individuals.
Plant physiologist Dr. Lawrence Zettler, of Illinois College, solved two key mysteries that have allowed botanists to grow and outplant the orchid, states a joint press release from the Nature Conservancy, the National Tropical Botanical Garden and the Hawai‘i Plant Extinction Prevention Program
Since the 1970s, Kaua‘i researcher Steve Perlman has monitored the decline of this rarest of Hawai‘i’s three native orchids, Platanthera holochila. The plant has tiny greenish blossoms but a large flowering shaft that can be a yard tall.
All that time, Perlman, through his work at the NTBG, had been patiently collecting seeds and sending them off to horticulturists, hoping someone could solve the mystery of how to propagate them. “Nobody could grow them,” he said.
Each year there were fewer plants, and until recently there was just one left in a Kaua‘i bog, 24 on Molokai and seven on West Maui.
“This orchid couldn’t wait,” Zettler said. “We were down to so few of them.”
In the 1980s, the Molokai population, inside the Nature Conservancy’s Kamakou Preserve, was protected with a fence, said Ed Misaki, conservancy director of Molokai programs.
“The orchid was already listed as an endangered species and this was the only occurrence within the preserve that we knew of. The population needed protection from wild pigs, which are a real threat, and the fence kept them at bay,” he said.
Because it is so vanishingly rare, the plant fell under the auspices of the state’s Plant Extinction Prevention (PEP) Program, which gathers all the available information on plants that have dropped to 50 or fewer in number, and tries to identify ways to improve their survival.
Hank Oppenheimer, Maui Nui PEP Coordinator, said neither of the other two Hawaiian orchids is as critically rare as the Platanthera, which was probably never common and is now found only on three islands. Populations of the Platanthera orchids have steadily declined or disappeared on several islands.
“It hasn’t been seen on O‘ahu since 1938,” Oppenheimer said.
The Hawaiian species is closely related to Platanthera orchids from Alaska and the Aleutians, and Perlman said he believes the seeds of their ancestors may have arrived stuck to the feet or feathers of migratory birds like the Pacific golden plover, which spends winters in Hawai‘i and summer in the Arctic.
Perlman said that several years ago he learned of Dr. Zettler, who specialized in the genus Platanthera.
Zettler was excited by the challenge of the fading Hawaiian orchid. In one of their early meetings on Molokai, Zettler placed packets of seeds in the soil around existing plants, and some of them grew. But he still could not get them to grow in the nursery.
After considerable work, he found that seeds would only germinate in complete darkness. But germination was only the first challenge.
Once sprouted, they did not thrive. His second discovery was that to grow well they require a symbiotic microscopic native soil fungus. These mycorrhizae derive energy from the orchids, while also providing nutrients like nitrogen and phosphorus to the plants.
In March of this year, Zettler and three of his undergraduate students flew to Hawai‘i with trays of tiny Platanthera holochila plantlets, grown from Molokai and Kaua‘i seed in sterile conditions. They were alive, but without their needed mycorrhizae, they would not thrive.
Perlman and Zettler, with Kaua‘i PEP Coordinator Wendy Kishida, outplanted the Kaua‘i seedlings in the Alaka‘i Swamp and, with Oppenheimer, the Molokai seedlings in the Kamakou Preserve — near enough to their parent plants that they were likely to link up with the mycorrhizae they needed.
Zettler also has seedlings from the Maui population, and the team anticipates planting some of them in West Maui in the future.
Initial checks indicate that most of the little transplanted orchids are doing fine, but it is not yet clear that they have located the mycorrhizae they need.
“The plants are looking good. We can see growth on six plants,” Perlman said. But Zettler added: “If they hook up with the right fungus, you’re going to see an explosion of growth. I’ve told them to expect some mortality as well. These orchids can have mortality of up to 90 percent from outplanting.”
“The good news is that we have a recipe that grows them now. We’ve already got a batch of 100 more,” Zettler said.
And the team is deciding whether to try to re-establish Platanthera holochila on O‘ahu, using either Kaua‘i or Molokai plants, which appear nearly identical to the early descriptions of the now-extinct O‘ahu populations.