Brother’s Keeper: Discovering Hibiscadelphus on West Maui

By Steve Perlman, Plant Extinction Prevention Program, Statewide Specialist

There we were, three botanists deep down a vertical slope in the remote mountains of West Maui, in the biologically rich Kaua‘ula Valley, preparing to conclude a long day of field work for the Plant Extinction Prevention (PEP) Program. It was nearly five o’clock and we were still a couple of hours’ hike away from our camp but taking one last look through his binoculars, my colleague Hank Oppenheimer pointed and said, “What’s that tree two ridges over?”

“It looks like Hibiscadelphus to me,” I answered. Although we were surrounded by cliffs and high peaks, Keahi Bustamente said he saw a way to reach the tree and so, overcome with the unexpected rush of excitement, we agreed to embark on the adventure.

An Incredible Discovery

After crossing two nearly vertical gulches, I waited for Keahi and Hank, so the three of us could enter the forest area together for what we were sure would be an incredible discovery. When I saw the fruit and Hank spotted the flowers, there was no doubt in our minds: we had discovered a new species of Hibiscadelphus.

While most people are familiar with commonly cultivated hibiscus, far fewer ever see Hawai‘i’s native hibiscus with flowers that range in color from red, pink, and white to orange and the bright yellow Hibiscus brackenridgei — Hawai‘i’s state flower.

Even more rare is the incredibly unique endemic genus Hibiscadelphus of which six of the seven named species are already extinct in the wild. Hawaiians call it hau kuahiwi meaning mountain hibiscus. Early 20th century botanist Joseph F. Rock first named the genus in 1911 for a species he worked with, naming it Hibiscadelphus — literally “brother of Hibiscus.”

Only one species — H. wilderianaus — represented by a single tree, had ever been found on East Maui and Hibiscadelphus was completely unknown on West Maui before we discovered this population of about 25 trees.

The Long Way Back

By the time we had collected flowers, fruit, seeds, and photographs, it was getting dark. We started up the cliffs and tried to return to camp by going straight up. Bad idea. We ended up using ropes and went a way we did not want to ever repeat. Fortunately, each of us carried head lamps, allowing us to make it back to camp by 9 p.m..

After our discovery, we decided to compare it with all known Hibiscadelphus in consultation with leading experts studying the Malvaceae family who confirmed it was indeed new to science. In subsequent field trips, our PEP team explored further and has since identified three sites populated by nearly 75 trees.

Hibiscadelphus stellatus

After considering a name for this plant, we decided on Hibiscadelphus stellatus. The Latin species name stellatus means star-shaped and alludes to the stellate hairs or pubescence. Stellatus also acknowledges the stellar (outstanding) beauty of the flower. The key differences between the West Maui Hibiscadelphus and its closest relative, H. wilderianus, are the dense white or tan stellate hairs on leaves, stems, bracts and larger purple colored flowers, yellow colored within. The flowers of Hibiscadelphus attract endemic honeycreeper birds whose bills match the decurved flowers, allowing the birds to drink the sweet nectar and cross-pollinate the flowers.

Following peer review and acceptance, our description of Hibiscadelphus stellatus was published in journal PhytoKeys 39: (pgs. 65-75) in 2014. The plant was also meticulously illustrated by Alice Tangerini, a staff illustrator at the Smithsonian Institution’s National Museum of Natural History, Department of Botany.

Preventing Plant Extinction Together

For those of us who work to save these unique plants, we see them as jewels of creation. For me personally, I’d like to think that all of us care about saving biodiversity because extinction truly is forever. This discovery, a great success for the PEP Program, is also a success for NTBG because together, we’re saving plants.

In 2014, Steve assumed the role of statewide specialist for PEP, concentrating on rough terrain field work on Kaua‘i and across the state. Steve is based at PEP’s Kaua‘i office located inside NTBG’s Botanical Research Center, allowing him and PEP staff to partner with NTBG. The PEP program’s Kaua‘i office has been housed at NTBG since its beginning as the goals of both are the same — to prevent plant extinction. Together NTBG and PEP locate, collect, and monitor Hawai‘i’s most endangered plants in the face of threats like introduced weeds, rats, feral ungulates (especially goats, pigs and deer), habitat loss, and disease. Among PEP’s goals are collecting seeds for long-term storage and growing endangered species in micropropagation tissue labs.

Currently, around 450 Hawaiian plant species are federally listed as endangered, far more than any other U.S. state. While more than 130 of the more than 1,350 species in the Hawaiian flora have gone extinct in the wild, Hawai‘i has experienced zero plant extinctions since the establishment of PEP in 2001. Today the PEP Program has botanists working on Kaua‘i, O‘ahu, Maui, Moloka‘i, Lāna‘i, and Hawai‘i Island. Learn more:

About PEP

The Plant Extinction Prevention (PEP) Program, operates as a project of the Pacific Cooperative Studies Unit of the University of Hawai‘i. PEP focuses on conserving the rarest of rare plants —238 Hawaiian species with 50 or fewer known wild individuals. Research Biologist Steve Perlman, who has worked for and with NTBG since 1972, played a central role in the development of the PEP Program, even giving the program its name.

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