By Ken Wood, Senior Research Biologist
Remote volcanic islands are supremely unique in their species composition as a result of natural long distance dispersal events that brought random plants and animals across the great expanse of ocean from fringing continents. Isolation and time have greatly increased the diversity of species on Kauaʻi with sublime plant and animal relationships and mysterious adaptive radiations. The extraordinary diversity of the Hawaiian flora lies close to my heart, and within this flora I have taken a keen interest in a group of species belonging to the genus Melicope, a member of the Rutaceae or orange family.
Melicope (called alani in Hawaiian) most likely arrived via migratory birds over five million years ago. It was William Hillebrand, author of the first Flora of the Hawaiian Islands (1888) whose writings introduced me to what was then called Pelea, a genus found only in Hawaiʻi and the Marquesas Islands. As the result of DNA research, the name Pelea was subsequently changed to the more widely distributed genus Melicope. Botanists in Hawaiʻi now recognize 54 species, making Melicope the largest radiation of woody plants in the Hawaiian Islands.
Many in Hawaiʻi are familiar with the mokihana (Melicope anisata) tree. With its enchanting anise scent, mokihana’s cube-shaped fruit is strung together to form the treasured lei of Kauaʻi, yet many of the other extraordinary species of Melicope are not well known. In the Flora of the Hawaiian Islands, published by Wagner et al. (1990), there were nine species of Melicope on Kauaʻi that were thought to be possibly extinct. Many had not been documented for more than one hundred years.
Subsequently, NTBG scientists and their partners rediscovered, mapped and made conservation collections of eight of those species, which bodes well for preventing their extinction, yet funding is continually needed to monitor and conserve them. One beautiful pubescent-leaved species, Melicope nealae (named after Marie C. Neal [1889-1965], a former botanist at Bishop Museum) remained elusive until a single individual was finally located by NTBG in 2019.
Prior to the rediscovery, NTBG had received several grants over the years to search for this missing species, but it took around thirty years to finally make the rediscovery. NTBG conservation scientist Dr. Seana Walsh, who has acquired grants for making conservation collections of several Melicope species, secured funding from the Tree Gene Conservation Partnership to work with M. nealae, and in the process a second colony of ten trees was discovered by NTBG and our partners with the Plant Extinction Prevention Program.
Melicope stonei, Illustration by Alice Tangerini
To date, we have collected seeds from both colonies. Another species Seana acquired funds for was the tall and elegant Melicope stonei, discovered by NTBG senior research botanist Dr. David Lorence in the mesic forests of Kōke‘e. We continue to monitor and conserve this taxon today.
When we consider the great floristic diversity of Kaua‘i, with more than 250 unique plant species that occur nowhere else in the world, time is truly of the essence for their conservation, and we are continuingly in need of funding for this effort. Long live the forests of Kaua‘i and those who support the diversity of life! After all, it was the forests from which we co-evolved and emerged, and the abundance of its species that nurtured us in need.
