From Plant Press, Vol. 19, No. 4, October 2016.
By Marc Appelhans & Warren Wagner
We recently described the species Melicope oppenheimeri in the journal PhytoKeys together with Ken Wood from the National Tropical Botanical Garden (Kaua`i). New species descriptions are probably published nearly every day, but this new Melicope species is special because it ranks among the rarest species on this planet. It is known only from a single valley on West Maui and only seven individual trees have been documented so far. Out of these seven trees, only three are alive today. Considering this minuscule number of individual trees, the species falls under the IUCN Red List category Critically Endangered.
Measures have already begun to prevent the extinction of Melicope oppenheimeri. Botanists of the Hawaii Plant Extinction Prevention Program (PEPP) are monitoring the species and two plants that have been produced by air-layering are currently grown at the Olinda Rare Plant Facility on Maui.
The Hawaiian Islands are a prime example for adaptive radiations on an Oceanic Archipelagoes and about ten percent of the successful colonizing lineages have diversified into species-rich lineages within the islands. In the past two centuries, the Hawaiian Islands also are a prime example of the major negative influence of humankind on our environment. Many species have become extinct or are extremely rare today. This trend can be observed in Hawaiian Melicope, which consists of 49 currently accepted species and therefore is the most species-rich Hawaiian radiation of woody plants. Five species are regarded as possibly extinct and another 23 species are either federally listed as endangered or are considered to be species of concern.