Scientific Name: Acacia koa
Endemic: All HI except Kaho’olawe and Ni’ihau
Description: These are large trees that on other islands, mainly on Kaua’i, Maui and Hawai’i that can reach over 100 ft. tall. It is easily distinguished by its light colored, flattened out, sickle shaped, modified stems (which look like its’ leaves). These special stems called phyllodes are packed with chlorophyll and take the place of its true leaves in more mature plants. When a seedling, the koa plant has bipinnate compound leaves, much like its other non-native cousin the koa haole.
Distribution: This endemic plant is often dominant in dry-wet forests on all of the main islands except Ni’ihau and Kaho’olawe. On O’ahu, koa is now restricted to mesic forests usually above 1000-1500 ft. It was probably found much lower than that in the past.
Landscape Use: Koa trees are beautiful shade trees for the landscape and should be used more often. People always have the misconception that koa can only grow in high elevation areas but that is completly false. We have one planted in Waimanalo at maybe 30ft. above sea level and its doing great! Another misconception is that it will become too large. Yes, naturally koa can be a very large tree, but, those trees are hundreds of years old! Still people plant much larger and faster growing trees like monkeypod or albezias. Generally, the koa trees in landscapes will be about 20-30 ft. tall. Koa is also very easy to take care of and requires little watering once established in the ground. The only pests you should worry about are stem borers. If you see a stem or branch beginning to dry out, immediately cut it off to prevent the bug from boring deeper into the plant.
Additional Info: Koa wood is highly valued and is used to make numerous items from canoes to hair picks. Today, because of increasing rarity in native plants, perhaps we should find alternative (non-native) trees to make our belongings out of. Instead of chopping down a Koa, ‘Ohi’a , Lama, or some other native tree, why not make something out of an invasive alien tree like java plum, cook pine, kiawe or strawberry guava, all of which have beautiful wood also! By doing this you help eradicate invasive aliens doing your part to preserve Hawai’i’s native forest treasures.
Koa