Nellie Sugii explains how micropropagation saved a critically endangered Hawaiian shrub.
In 2004, the last remnants of an exceedingly rare Hawaiian species, Cyanea grimesiana ssp. grimesiana, bloomed and set fruit in the wild. Known only from the leeward slopes of the southern Ko‘olau Mountains on the island of O‘ahu, this shrub is one of seventy-eight species within an endemic Hawaiian genus commonly known as haha. The species could be found surrounded by koa (Acacia koa) and other common forest trees, and it has been rare since it was first documented in the wild in 1819. Significant surveys occurred in the 1990s, and by 2004, only two mature wild plants remained, with no evidence of recruitment or any significant ex situ collections. The situation became dire.
At the time, I was several years into my career as a researcher for the Lyon Arboretum’s Hawaiian Rare Plant Program, where I’m now the program manager. Our work focuses on rescuing and recovering Hawai‘i’s most critically endangered plants, storing germplasm for ex situ conservation, and providing plants for in situ restoration. Our micropropagation laboratory is central to this effort—a surreal indoor space where more than 170 of Hawai’i’s rarest and endangered plant species are grown collectively in tens of thousands of test tubes. I often describe it as “plant conservation through the looking glass.”
When the hāhā remnants flowered, our team worked with collaborators, including the Plant Extinction Prevention Program, the US Fish and Wildlife Service, and the US Army’s Natural Resource Program, to plan for protecting the species in the micropropagation facility. Field biologists monitored the two plants. The flowers emerged as white, arching tubes, streaked with vibrant purple. The fruits then ripened into orange, fleshy capsules. The biologists carefully collected the fruit and brought it to the micropropagation lab for germination. We knew it was a heavy responsibility when the precious seeds arrived, but excitement ran through the lab as we sorted, cleaned, and prepped the seeds for in vitro seed sowing.
Micropropagation gained recognition as a viable propagation method for commercial applications in the 1960s, but the technique was initially viewed suspiciously due to associated terms and applied technologies such as cloning, anexic seed sowing, ovulo culture, and organogenesis. To some, even at the Lyon Arboretum, these technologies seemed contrary to conservation theologies of preservation and genetic integrity. Yet micropropagation has gradually proven itself as a useful rescue and recovery tool. It can be used to germinate immature seeds and rescue embryos from aborted fruit. It’s also used for cloning wild plants at risk of extirpation in order to preserve genetic representation and establish clonal lines of its seedling progeny for restoration.
After the hāhā germinated in our lab, we learned that the final wild remnants had altogether succumbed—the species no longer existed in the wild. This knowledge brought bittersweet feelings as we watched the seeds germinate in the petri dishes and eventually grow into seedlings that we placed into individual test tubes. We knew that it was now our responsibility to establish perpetuity for this species by establishing clonal lines of the seedlings through microcuttings and maintaining the in vitro germplasm collection until a safe and secure restoration site free of threats became available.
We learned that the final wild remnants had altogether succumbed—the species no longer existed in the wild.
Approximately 88 percent of the native plants on the Hawaiian Archipelago naturally occur nowhere else in the world. This rich biodiversity serves as a unique example of insular evolution, but its fragility is evident by the scale of species on the brink of extinction. According to listings by the US Fish and Wildlife, about one-half of the nation’s threatened and endangered plant taxa are from Hawai‘i. Of the five hundred Hawaiian species assessed for the International Union for Conservation of Nature’s Red List, about 87 percent are classified as endangered or threatened. Let us not mention the hundreds of rapidly declining species that are missing from either list but are at risk of extinction.
On August 23, 2013, over nine years after the eventful collection date, I gathered at a site in the Ko‘olau Mountains with a group of individuals involved in the conservation of Cyanea grimesiana ssp. grimesiana. A festive mood spread among us. We had long awaited the moment when we would bring this species and a few associated plants back to its native habitat, within the Mānoa Cliff Forest Restoration site. Our small group of friends and family—even a few children—made our way through a forest of an invasive bamboo that had taken hold in the area. A few of our team wore backpacks containing plants, and most everyone else carried trays of plants or tools in our hands. A space opened in the bamboo, and a pocket (or kipuka) of near-intact native forest appeared before us. For those seeing it for the first time, the beauty of the area took our breath away. We all acknowledged that the enclosure represented a new beginning for this hāhā.
By 2021, the original Mānoa Cliff plantings had matured. The hāhā plants flower and produce fruit, and the seeds are collected and sowed for restoration purposes or stored in our program’s seed conservation laboratory. We have now stored thousands of seeds from the different plants, and we continue to maintain the original clonal lines in the micropropagation lab, with long-term cryopreservation being our future and final ex situ storage goal. With many hands and great effort, we have brought Cyanea grimesiana ssp. grimesiana back home.
Nellie Sugii is the acting director of the Lyon Arboretum, part of the University of Hawai’i, and is the manager of the Hawaiian Rare Plant Program.
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