Thanks to our community of staff, partners, and supporters, we celebrated many wins for tropical plants this year. With each discovery, initiative, and innovation, we are growing a brighter future for generations of plants and people together.
Kokiʻo kea (Hibiscus waimeae subsp. hannerae)
In February, NTBG completed a major campaign to safeguard endangered endemic trees of Kauaʻi in our Limahuli Preserve. Over the last three years, about 540 individual trees have been outplanted with more on the way.
These trees belong to eleven different species, including two types of native Hibiscus and two varieties of loulu palms (Pritchardia sp.). Several of these species are at the brink of extinction, but we’ve conducted many hours of surveys to collect ripe seed and improve propagation success. Our preserve team has been mitigating rats, slugs, and weeds to create ideal habitat and give the new small trees the best possible start. The results have been published in the scientific journal Plants, People, Planet. This work was funded by Fondation Franklinia and National Geographic Society.
Left: ʻŌhā wai (Clermontia hanaulaensis), photo by Hank Oppenheimer. Right: Koʻokoʻolau (Bidens wailele) colored pencil and watercolor illustration by Wendy Hollender.
NTBG and collaborators published reports detailing two previously undescribed plant species this year.
In June, NTBG and collaborators from the Plant Extinction Prevention Program and the Smithsonian published a report describing a new species of ʻōhā wai, Clermontia hanaulaensis, found exclusively in a small section of Mauna Kahālāwai in West Maui. Their paper was published in PhytoKeys.
Also in June, NTBG and collaborators published a paper detailing a highly unusual species of koʻokoʻolau, Bidens wailele, found only in remote parts of Kauaʻi’s rain-soaked interior. Their paper was published in the International Journal of Plant Sciences.
With an estimated 120-130 remaining Clermontia hanaulaensis and 700-800 Bidens wailele in their natural habitats, both species meet the IUCN Red List criteria to be listed as Critically Endangered. These reports provide valuable information that will help guide conservation efforts for these unique species.
From left: Mēhamehame (Flueggea neowawraea), ʻōhai (Sesbania tomentosa), and aʻe (Zanthoxylum hawaiiense)
As part of a cross cutting partnership*, NTBG helped submit a total of 113 new Global Tree Assessments to the IUCN Red List. These submissions mark the completion of assessments for all 336 native Hawaiian trees.
A staggering 90% of Hawai‘i’s flora is found nowhere else on Earth, and include a significantly higher proportion of threatened species compared to the global average. We hope these newly submitted assessments will contribute to a deeper understanding of the conservation status of these invaluable trees. The IUCN Red List has become the global authority on species conservation status and the assessment of all Hawaiʻi’s native trees help bring international attention to the conservation needs of Hawaiʻi’s irreplaceable plants.
* Partners include the State of Hawaiʻi Department of Land and Natural Resources Division of Forestry and Wildlife, and Laukahi.
ʻŌhai (Sesbania tomentosa)
Two studies published this year brought fascinating insights into the world of seeds.
NTBG’s Seana Walsh, Dustin Wolkis, and partners led a study to understand how well 21 different coastal plant species tolerate salinity during germination. This study holds particular importance in light of challenges associated with rising sea levels and the vulnerability of seeds amid changing habitat.
They found that although salinity tolerance varied among the 21 species, exposure to salinity generally reduced and delayed germination. Surprisingly, despite being one of the most endangered species in the study, ʻōhai (Sesbania tomentosa) was unaffected by high salinity. These findings can help guide coastal ecosystem conservation and restoration management decisions in the face of climate change. Their paper was published in the journal Annals of Botany.
Another study presented the results of a project that involved the discovery of a 30-year-old jar containing ʻōhai seeds in our herbarium. Emily Saling, a former Kupu member assigned to our Seed Lab, evaluated the viability of the 12 seed lots found in the jar. Not only did a significant number of seeds germinate, they did so surprisingly quickly! These findings give us hope for the conservation of this species, suggesting that even seeds stored in less than optimal conditions may remain highly viable for decades. Read more about the study via Oryx.
Landscaping outside of the ICTB at The Kampong includes species native to a Florida hardwood hammock dry habitat.
This year marks the opening of the International Center for Tropical Botany (ICTB) at The Kampong! The ICTB at The Kampong is a collaboration between NTBG and Florida International University and aims to develop research, education and outreach programs related to tropical botany, integrating the research programs of a faculty with global presence in tropical regions.
The new facility builds upon a decades-long history of tropical plant collection and research at the home and garden of botanist David Fairchild, who purchased and named The Kampong in 1916.
Read more about how the ICTB at The Kampong is growing the next generation of botanists.
This year, NTBG completed a project which involved revisiting 10 outplanted Polyscias bisattenuata populations. We examined both genetic and environmental data to understand the factors influencing the survival and overall health of this special tree. Our findings indicated that the initial survival of the trees is influenced by the extent of weed exposure and competition. However, once established, the trees exhibit greater vigor in lower elevation sites, suggesting the possibility of growing them in lowland areas as well as cultivating them in a horticultural setting.
The rooted Laukahi cutting producing seeds in our nursery
Back in 2022 with the help of the Mamba, we were able to retrieve a cutting of the rare laukahi (Plantago princeps var. anomala), a critically endangered cliff-dwelling plant found only on Kauaʻi.
Once the laukahi cutting made its way to our Nursery, staff set to work on rooting the cutting using a mixture of educated guesswork, a new propagation technique, and by keeping the cutting in a climate-controlled lab.
All the investment and passion paid off: the laukahi cutting not only rooted, but this year it produced seeds! Several of these seeds have germinated and are surviving in our nursery. Our nursery was also able to provide our Seed Bank with approximately 500 seeds for safekeeping.
Limahuli Garden & Preserve, with the help of many partners and community members, is now home to 82 kalo (taro) cultivars. This represents a nearly complete collection of known kalo varieties, a precious resource that preserves ancestral relationships and critical crop diversity. A special thanks to the Amy B.H. Greenwell Ethnobotanical Garden and Kohala Center for their support and partnership this year.