Uhiuhi (Mezoneuron kavaiense; formerly Caesalpinia kavaiensis) – The value of cultivation


    Back in the mid-1990s, it was impossible to get seeds of O‘ahu uhiuhi for cultivation. This was understandable. At the time, there were only about three dozen wild uhiuhi left on O‘ahu, all mercilessly being attacked by the alien black twig borer. State botanists were diligently and tirelessly collecting seeds from these last trees for long-term storage until some plan could be formulated to deal with this foe and reintroduce uhiuhi back into O‘ahu’s remaining dry forests. Seeds from Big Island uhiuhi were nearly as hard to come by. Howver, I was determined to grow and learn about this plant and was fortunate enough to acquire a few seeds from an uhiuhi already in cultivation. When one of the seedlings was large enough, I planted it out on the campus of Leeward Community College (LCC) where I was then an Instructor of Biology. The uhiuhi did amazingly well, growing into a vigorous fruiting tree that almost never was attacked by borers. 

    I left LCC in 1998, and five years later Frani Okamoto became the LCC Shadehouse & Native Plant Collection Manager. In 2004, Frani and I heard about four orphaned O‘ahu uhiuhi being kept in the State’s (DOFAW) Rare Plant Facility at Pahole. The story was, as best as we could determine, that parent plant documentation on the four uhiuhi was in question so the plants had not been used in a reforestation project but remained at the Pahole facility. Frani and I felt this was the perfect opportunity to get the O‘ahu uhiuhi into cultivation. We convinced DOFAW (and the O‘ahu Army Natural Resources Program because two of the uhiuhi belonged to them) that they should give the four plants to Frani who would plant them out on the LCC campus. 

    It was a sad but necessary day when we dug up and removed the eight-year-old Big Island uhiuhi from LCC; the O‘ahu uhiuhi had begun to flower and we could not risk producing hybrid seeds from the two island varieties. Like the Big Island uhiuhi before them, the O‘ahu plants grew vigorously at LCC. They also started to produce an enormous amount of seeds that Frani religiously collected and stored; by 2009, she had over 1,700 seeds. In 2008, Frani obtained endangered species commercial sale tags, and, for the very first time, O‘ahu uhiuhi were available for purchase by the public. In addition, Frani has given 2,550 seeds (2005-2010) back to the Rare Plant Facility at Pahole and Lyon Arboretum’s Seed Conservation Laboratory. DOFAW plans to propagate the seeds for test plantings throughout the Wai‘anae Mountains to locate viable uhiuhi recovery sites. This way, the much more valuable wild-plant seeds collected by botanists many years ago will not be wasted on failed attempts to find the uhiuhi a safe home on O‘ahu.