NTBG’s Fern Lab — Save and Restore

By Léo Azambuja

On the cover: NTBG Fern Lab Technician Emily Sezate is seen here at the nursery holding an Asplenium nidus, or ekaha. Photo by Léo Azambuja

The Hawaiian Islands are home to one of the most distinctive fern floras on Earth, with three quarters of more than 140 native fern species being endemic. Hawaiian ferns evolved for millions of years to populate many dry, mesic and wet forests, representing as much as 20 percent of the native flora. As such, ferns play a vital role in our watersheds, filtering and retaining water, and also providing critical habitat for living creatures.

“Ferns are absolutely important to ecosystem function, filtering moisture out of passing clouds as epiphytes on trees and then absorbing that moisture as terrestrial ferns. Some moths lay their eggs on the leaves of some fern species,” said Mike DeMotta, Curator of Living Collections at the National Tropical Botanical Garden.

In April 2022, NTBG officially opened its Fern Lab in Lawa‘i Valley. But the garden’s affair with ferns goes back many years. NTBG started growing ferns in 2007 as part of a research project conducted by Dr. Ruth Arugaiuja of Estonia, a research associate at NTBG and Hawaiian fern expert, according to DeMotta. The Fern Lab itself would become a funded program this year.

DeMotta said the Fern Lab’s main goal is to develop the protocols to be able to grow common and rare native ferns, with conservation and restoration in mind. It’s the only facility on Kaua‘i — and likely in the entire state — focused on Hawaiian fern propagation, according to DeMotta.

UV light keeping the ferns clean at the lab. Photo by Léo Azambuja

“The work we do is pretty unique. That is, documenting the protocols to grow all the different native fern species,” DeMotta said.

Fern Lab Technician Emily Sezate was an intern at the lab through an internship program at Kupu Hawai‘i before taking the job full-time a month after the lab opened. At any given time, there will be more than 60 different species of ferns being grown on the shelves of the Fern Lab — small in size but large in importance.

“We do a lot of research projects here. Not a lot of research has been done on ferns, so I’m kind of creating new protocols for growing them. I’m finding out the viability of how long certain spores last. I’ve used some herbarium sheets and sampled off of ferns that have been dried and pressed up in the herbarium since the 80s. And these are all plants from them,” said Sezate, pointing out the collection of ferns growing on the lab’s shelves. “So it’s like kind of testing our boundaries.”

Ferns and regular plants have some fundamental differences. Usually, regular plants propagate from seeds. Ferns, however, produce spores that germinate and share their genetics with other sprouted spores (gametophytes) through moisture in the soil, according to DeMotta. From there, they grow into small fern plants (sporophytes). Some ferns may also reproduce asexually, either by branching off of their underground stems or by spore sprouting without fertilization.

Fern Lab Technician Emily Sezate at the facility. Photo by Léo Azambuja

Out of 144 species of native ferns in the Islands, 38 are indigenous (they are native to Hawai‘i and elsewhere), and the remaining 106 are endemic, meaning they only happen here. If you include subspecies and varieties, the number of native ferns jumps to 167, with 84 percent being endemic.

At least 29 species of Hawaiian ferns are listed as rare and endangered, according to Daniel D. Palmer’s book, Hawai‘i’s Ferns and Fern Allies.

Sezate said her work has already shown that it is possible to grow dry-land ferns from spores stored four decades ago. In the future, it could potentially help to bring back species extinct in the wild, or to propagate seeds from plants that are almost impossible to reach due to habitat isolation.

She said she is researching the boundaries of ferns.

“I’m trying to figure out how long it takes some of them to grow, how long their spores will survive, what conditions,” said Sezate, adding a particular fern species, Asplenium dielmannii, was thought to be extinct for years. “Then one of our researchers found one population, got spores, raised 100 plants and put them back into the wild. And then I went and sampled those, and I’m doing the second generation. But these spores, they take three years to even make a tiny plant. So it’s a lot of maintenance.”

Starters at NTBG Fern Lab. Photo by Léo Azambuja

One of the main challenges at the Fern Lab is keeping the small ferns from being contaminated with fungi and algae. Air purifiers help, but it’s still a challenge. Once the ferns grow to a few inches tall, they are transferred to a nursery just outside the lab. Depending on where the ferns will be replanted, NTBG staff will either let them grow a little more or just replant them while they’re still small.

“If they’re being backpacked up into Limahuli Preserve, they don’t want to carry huge pots with them, especially if they have 20 (plants), then we’ll leave them this size,” said Sezate, pointing to small fern samples. “But then, the hardest part with them being this size is that pigs and everything could eat them. And they’re more likely to die.”

A lot of the ferns are taken to Limahuli Preserve, near the end of the road in Ha‘ena, Kaua‘i’s North Shore. Some are taken to Kahanu Garden on Maui’s Hana Coast, and others might go to Koke‘e on Kaua‘i’s Westside, according to Sezate.

“We try to put them wherever we can; it just depends on each project,” Sezate said.

Starters at NTBG Fern Lab. Photo by Léo Azambuja

At least three species of ferns being grown in the lab are critically endangered, some with less than 50 plants in the wild.

“The Doryopteris angelica that we have here is only known on Kaua‘i,” Sezate said. “I’ve only seen one population in the wild. I’m not out much but I don’t know if there are that many, it’s probably only a few plants.”

The biodiversity of our native habitats is something really important, she said. If there are only a few species of plants left, the whole ecosystem will crash. Pollinators have specific plants and trees they seek for food or shelter, and the understory is also really important to the whole system. If you take one piece out, eventually another piece falls, creating a chain reaction because it’s all connected. And then the ferns play a huge role in soaking up carbon dioxide from the atmosphere

“We have all these flowering plants we’re focusing on, but a lot of ferns are going extinct. And ferns have a huge role in the forest, they soak up a lot of carbon and they do mitigation of water,” Sezate said. Ferns also provide habitat for insects, birds and land snails. Additionally, ferns and have a deep cultural background in Hawai‘i.

“Nobody really thinks of ferns,” she said. “Now that they’re disappearing, it’s time that we have to jump on top of it. Otherwise, they’re just all going to go extinct.”

NTBG is a nonprofit organization dedicated to discovering, saving and studying the world’s tropical plants and sharing what is learned. They have five botanical gardens, preserves and research facilities encompassing nearly 2,000 acres with locations in Hawai‘i and Florida. NTBG’s support comes primarily from donations from individuals and grants from public and private foundations.

Visit www.ntbg.org for information on programs, events, visits and how to become a member.