Hawaiʻi has more endangered plants than all other U.S. states combined.
A total of 18 native species are so rare that only a single plant remains in the wild.
Botanists with the Plant Extinction Prevention Program monitor these critically endangered individuals. And they’ve been working to ensure that when these last plants die, their entire species doesn’t vanish.
Each of these species has been successfully preserved in seed banks and nurseries with the hope that they may flourish in Hawaiʻi’s native forests in the future.
The bellflowers
Cyanea dunbariae, endemic to the island of Molokaʻi, is a member of the bellflower family. This species co-evolved with the native honeycreepers. When it’s in bloom, the shape of its long flowers matches the curve of a honeycreeper’s beak.
Matt Keir, a botanist with the state Division of Forestry and Wildlife and a member of PEPP, said that many of the original honeycreepers who pollinated species like C. dunbariae are likely extinct, which may have contributed to the plant’s decline.
C. dunbariae has been successfully cultivated in nurseries. To help this bellflower and its relatives thrive in the wild one day, Keir said his team is working to identify habitats where remaining honeycreepers, like the ʻiʻiwi, can serve as pollinators.
“We see these ecosystems begin to fall apart, and we’re picking up every piece along the way,” Keir said.
Cyanea heluensis, a sister species found in West Maui, was discovered in 2010 by PEPP botanist Frank Oppenheimer.
This single individual on Mauna Kahālāwai is the only one of its species ever known to exist.
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— Cyanea dunbariae, a bellflower species endemic to Molokaʻi.
Cyanea dunbariae, a bellflower species endemic to Molokaʻi.
Hank Oppenheimer / Plant Extinction Prevention Program
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— Cyanea heluensis_Hank Oppenheimer_PEPP – Copy.jpg
Cyanea heluensis, a bellflower species endemic to West Maui.
Hank Oppenheimer / Plant Extinction Prevention Program
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— Cyanea cf. fernaldii, an undetermined bellflower species in East Hawaiʻi.
Cyanea cf. fernaldii, an undetermined bellflower species in East Hawaiʻi.
Josh VanDeMark / Plant Extinction Prevention Program
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— Delissea kauaiensis_Kauai PEPP – Copy.JPG
Delissea kauaiensis, a bellflower species endemic to Kauaʻi.
Plant Extinction Prevention Program
Similarly, a plant called Cyanea cf. fernaldii in the forests of East Hawaiʻi is so rare that PEPP is still working to determine exactly what species it is.
Keir said that it appears to be unlike any other Cyanea that they’ve identified on Hawaiʻi Island.
“We’ve been watching the last remaining plants, and now it’s just down to a single individual,” he said.
And the last wild individual of Delissea kauaiensis, a bellflower endemic to Kauaʻi, may already be gone.
“We suspect that there is maybe just one or perhaps no plants left of this species in the wild,” Keir said.
Like its bellflower relatives, D. kauaiensis is vulnerable to invasive pests. Slugs eat their seedlings, rats devour their berries, and feral animals like pigs and goats trample their delicate roots and stalks.
Keir said that in order for the bellflowers to successfully repopulate in their native habitats, these pests have to be controlled.
“We need to protect them from the threats that cause their decline in the first place,” he said.
The mintless mints
Hank Oppenheimer
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Plant Extinction Prevention Program
Stenogyne kauaulaensis, species in the mint family that’s endemic to West Maui.
Stenogyne kauaulaensis, found in the mountains of West Maui, is a small, viny plant that grows in the thick, wet understory of Hawaiʻi’s native forests.
It’s in the mint family, but unlike the mints we use in foods and drinks, it doesn’t have a recognizable minty taste.
“The plants that are in Hawaiʻi are often called the mintless mints,” Keir said.
The mintiness was likely a natural defense against predators that Hawaiʻi’s mints have lost over time.
Phyllostegia waimeae is another species in the mint family. It’s endemic to Kauaʻi, where it grows along the sheer slopes of Waimea Canyon. PEPP botanists only know of one remaining individual, but they’re on the hunt for more.
“Waimea Canyon is very steep, and there’s lots of places to look,” Keir said.
Saving one species at a time
Melicope oppenheimeri, named after botanist Hank Oppenheimer who discovered Cyanea heluensis, is a woody shrub in the same family as many common citrus trees.
The last remaining wild plant of the species grows in Waiheʻe Valley in West Maui. One of the plant’s most distinctive features is its strange, star-shaped fruit.
Hank Oppenheimer
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Plant Extinction Prevention Program
Melicope oppenheimeri, a woody endemic shrub found only in West Maui.
Generally, this species is relatively long-lived. In good conditions, this shrub can survive for decades. But Keir said that a handful of individuals have died in quick succession in recent years, leaving just one M. oppenheimeri standing.
“I would not be surprised if it was also gone sometime in the next decade,” Keir said.
Holding vigil as the last wild plant in a native species dies is part of the job of PEPP botanists. But that doesn’t make the process any less heart-wrenching, Keir said.
“These are plants that we’ve known personally for many, many years,” he said. “We know we’re working with the treasures of Hawaiʻi.”
Still, Keir said he is confident that the descendants of these last wild plants, currently waiting in Hawaiʻi’s nurseries, seed banks, and protected reserves, will one day reclaim their place in the wild — with PEPP’s help, of course.
“Given enough time, I think there is no technical reason a plant needs to go extinct. We just need to not be overwhelmed by it and have the capacity to deal with them one by one,” Keir said.
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