By Ces Eltringham
As part of our Fall 2023 Internship Program, each intern was paired with a plant that holds particular significance at NTBG. Their task was to delve into and gain insights about their plant through the lens of NTBG’s various gardens, departments, and voices. Each intern crafted a story that captures their journey with their plant.
Originally from London, UK, Ces Eltringham has been working in horticulture for the past six years, beginning her journey working on a private estate in Scotland while completing her undergraduate degree in psychology at Edinburgh University. She then went on to earn a three-year diploma in botanical horticulture from Royal Botanic Gardens Kew.
For her final project, Ces wrote an article about the incredibly rare and special Cyanea kuhihewa, and the various NTBG staff and partners who have helped grow a brighter future for this plant.
In the Upper Limahuli Valley on the north shore of Kauaʻi there is a ledge accessible only by a fallen log hanging over an 800-foot waterfall. It was on this ledge that NTBG research biologist Ken Wood found himself in 1991, staring in disbelief at a group of 12 plants. Earlier that morning Ken and his colleagues had been discussing a narrow-leafed plant called Cyanea linearifolia which was last seen in 1957 and presumed extinct, but there it was, apparently alive and well. Ken collected a specimen and scurried back down the log to present it to his colleagues who eagerly agreed.
However, when the specimen was sent to Thomas Lammers, a botanist at the Field Museum in Chicago, he concluded that the finding was not, in fact, the long-lost Cyanea linearifolia, it was an entirely new species. The species was playfully named Cyanea kuhihewa, with “kuhihewa” meaning “to suppose wrongly” in Hawaiian language.
In 1992, when Hurricane ʻIniki struck Kauaʻi, 145-mph winds wreaked havoc on the island, wiping out huge swathes of native forest canopy. In the aftermath of the disaster an influx of opportunistic invasive plants recolonized devastated forests. In the face of these changes, the newly discovered population of Cyanea kuhihewa entered a quick decline. By 1997 only three wild trees remained in the Limahuli Valley and by 2003 the last known wild tree had died. “We thought we’d totally lost the opportunity to save [the species]. It’s not the first time that’s happened, but nevertheless it never gets any easier”, Ken recalled.
Fourteen years later, in 2017, things were looking hopeless. Then suddenly and unexpectedly, Ken Wood came face to face with an old friend. Ken and his team were on the final day of a 10-month project inventorying a valley much like Limahuli on Kauaʻi’s north shore. The project, funded by Kamehameha Schools, was comprised of a team of biologists working with The Nature Conservancy of Hawaiʻi (TNCH) and NTBG. In the words of Ken Wood, “[it] was the very last day and the very last flight in and we were coming down one of the fence line ridges going down a really steep slope to a drainage when we discovered the Cyanea kuhihewa. It was like ‘whew, what a rush!’”
Two mature and one juvenile plant along with 15 tiny seedlings were found and, having lost the last opportunity to protect this unique species, every precaution was taken. Rat traps were immediately set up, and Kamehameha Schools, TNCH, and NTBG implemented a system to closely monitor the population.
By August 2018 fruit had been collected and 90 seeds were sent to Lyon Arboretum on Oʻahu. Greenhouse survival rates for Cyanea kuhihewa were notoriously low at this time and with so few seeds available the loss of single seedling would mean the permanent loss of important genetic information. Fortunately, Lyon Arboretum had a solution.
Lyon’s laboratory is filled with more than 30,000 test tubes, each containing a miniature version of Hawaiʻi’s most critically endangered plants, each growing as a clone These are generated through a practice known as tissue culture in which seeds are germinated and then the very young cells are taken and exposed to a fine balance of chemicals causing them to develop into an entirely new plant. In this way one seed can produce many progeny, increasing the likelihood of success. By the end of 2018, 42 Cyanea kuhihewa clones were alive and well in the lab at Lyon.
It was Mike DeMotta, NTBG’s former curator of living collections, who was responsible for bridging the gap between Lyon Arboretum and NTBG’s nursery. “Mike would fly in from Oʻahu and they’d come straight from the lab over there, so they’d be on a plane, get to our nursery and then we’d have to quarantine them”,
But it was a rocky start.
Rhian Campbell, NTBG’s nursery manager, explained why plants were lost in the beginning. “They seemed very sensitive to heat, and especially to fungal disease when it’s hot. The two things work in tandem to kill them off, so we had to really think about how to keep [them] alive.”
What does a team do when faced with such a daunting challenge? Simple, “we brainstorm it out.” says Rhian. “We research the microclimates, the environments, and try to understand former growing conditions as best we can.”
The nursery team’s efforts led to a huge breakthrough. Cyanea kuhihewa is found in wet forest at an elevation of around 1,650 ft (500 m) in very different conditions to the lowland conservation nursery so Rhian and the team tried to grow the plants in the fern lab in a climate controlled, sterile environment.
Rhian says the survival rates were striking.
A further breakthrough occurred soon after. Hayley Walcher, a horticulture specialist at NTBG’s conservation nursery, has eagerly pursued a better understanding of soil microbial communities. Bacteria and fungi are some of the microscopic organisms that live in the soil. Through the relationships that they form with plants, they can aid nutrient absorption, enhance immunity, and stimulate growth. Interestingly, many native Hawaiian plants depend heavily on these relationships, so it was logical for Hayley to start including native soil in the potting mixes. It turns out to have been the secret ingredient for growing many of Hawaiʻi’s rare plants, Cyanea kuhihewa included.
By 2020 freshly collected seeds were arriving at the NTBG nursery, and with improved growing protocols established, the team was ready to go “We had around 16 seedlings and then more sprouted and it was 30 and we just kept going with it. It was very exciting,” says Hayley.
After germination, plants remain under the care of Hayley and Rhian for the first eight months to a year before they are sent by helicopter to be outplanted in the Upper Limahuli Preserve.
The Upper Preserve represents about 400 of the 1,000-acre Limahuli Valley and is only accessible to the intrepid team of NTBG conservation staff who helicopter up to the site every week and remain, for five days at a time. It is also the site where Cyanea kuhihewa was first discovered more than 30 years ago.
“[We] have the privilege and responsibility and opportunity to help get these plants back to their home environment says Uma Nagendra, conservation operations manager for Limahuli Preserve.
Since 2020 plants have been flown into the Upper Preserve in batches of up to two dozen plants. There they are carefully packaged into buckets and hiked out to one of three planting sites. These sites have been carefully selected to be as close as possible to the conditions in which the plants were first found: soft and fertile dirt walls of gulches carved out by streams.
However, these plants are far from being out of the woods, even when planted back into them. After they’ve been outplanted, the plants face significant threats and even the healthiest plants can quickly succumb to slugs and fungal diseases.
Showing me a photo of a thriving C. kuhihewa, Uma says,“This is our champion, one of the first plants that was planted.”, but even seeming success stories can have an unhappy ending. For this remarkable plant that had more than quadrupled in size in less than a year, it ultimately succumbed to a fungal pathogen. Despite ongoing threats, the NTBG has achieved a 79% survival rate which is encouragingly high.
As recently as June 2022 a new colony of Cyanea kuhihewa comprised of two healthy mature plants and 12 offspring was found just 70 meters from the population discovered in 2017. Today six large individuals and a plethora of seedlings are now thriving across the two wild populations and four of these wild plants are newly producing seeds. A further 48 individuals are growing steadily in the Upper Limahuli Preserve, and 48 more plants are in the nursery, ready to be outplanted.
With such small numbers, NTBG is not just relying on wild and planted populations to save this species. In NTBG’s seed lab, the soporific hum of freezers hints at the presence of the 17 million seeds which are kept safe in storage. Seed banking is a common conservation practice wherein seeds are dried and then frozen to prolong their storage capacity. This, according to Dustin Wolkis, NTBG’s seed bank curator and laboratory manager, provides a “genetic safety net” that secures the possibility of future restoration projects in the face of disasters like Hurricane ʻIniki. The seed lab currently holds 7,450 Cyanea kuhihewa seeds which are expected to remain viable for up to a decade in storage. In time, Dustin’s pioneering research into seed storage behavior may prove to have unlocked the secret to extending seed storage longevity by decades or even centuries. In the words of Ken Wood, “we don’t really know what other miracles could be hidden in the folds of time…” Hopefully, a bright future for Cyanea kuhihewa is amongst them.
