Native Hawaiian Garden (7722)

‘Ahakea (Bobea sandwicensis) – A tradition preserved in fiberglass

In pre-contact times, Hawaiian canoes were hued from the giant koa (Acacia koa) of native mesic forests. Besides its size, koa was a particularly good choice since the wood is relatively soft; making a canoe from a koa tree consists largely of hollowing out and discarding much of its wood. No sane Hawaiian would have attempted to make a canoe from the giant native mehamehame (Flueggea neowawraea) of Hawai‘i’s dry forests that are just as large as koa but have incredibly hard wood. Unfortunately, the soft wood of koa is not well-suited for the gunwales of a canoe, the upper edge that is repeatedly struck by paddles. Therefore, Hawaiians used the more durable ‘ahakea for this part of the canoe. Waterproofed and protected with kukui nut oil, ‘ahakea wood turns a beautiful golden yellow.

After western contact, canoe construction changed. The old materials, koa and ‘ahakea, were replaced with imported and milled woods. In addition, western boat-building techniques replaced traditional methods. Still, canoe-builders would often paint the gunwales of the new canoe yellow to mimic the past gunwales made of ‘ahakea. Today in Hawai‘i, wooden canoes are rare, most being constructed entirely of fiberglass and plastics. Still, some builders carry on the tradition and while the hull of their canoe may be any one of many modern colors, the gunwales are still pigmented yellow. I wonder how many of these builders, or paddlers for that matter, know the origins of the yellow gunwales on their modern fiberglass canoe.

Habitat & Appearance: Bobea sandwicensis is one of four Bobea species named ‘ahakea. According to Wagner et al. (1990), it grows wild in the dry to mesic forests and lava flows of O‘ahu, Moloka‘i, Lāna‘i and Maui. (I have only personally seen this tree in the dry forests of O‘ahu.) Healthy B. sandwicensis, a rarity, are beautiful trees with light green leaves and pinkish-white scalloped bark growing to about 30 feet tall.

Ripe and developing ‘ahakea fruit (Photograph courtesy of J.K. Obata via G.D. Carr ©). ‘Ahakea seedlings without and with first true leaves. Header photograph of ‘ahakea flower courtesy of David Eickhoff CC BY 2.0.

‘Ahakea in Hawaiian Culture: In addition to using ‘ahakea for canoes, Hawaiians used the wood to frame the opening of their hale (Krauss, 1993). The wood was also fashioned into paddles and papa ku‘i ‘ai or kalo-pounding boards (Malo, 1951). ‘Ahakea bark was one ingredient for a poultice used for abscesses (Chun, 1994).

Collecting Seeds: Because ‘ahakea are (nearly) functionally dioecious, the first challenge is finding a fruit-producing tree. Fruits with viable seeds are about the size of a blueberry with light-yellow, wedge-shaped (3/8 inch long) seeds. Confusingly, ‘ahakea will produce smaller fruits containing smaller, non-viable seeds. The fruits ripen and turn purple in the spring and summer. Seeds stored in a refrigerator remain viable for at least ten years.

Growing from Seed: After sterilizing in bleach, soak the seeds for 5-7 days in a shallow pan of clean water before sowing in vermiculite. Using Method One, the seeds will begin sprouting in 4-5 weeks and continue for several more weeks. Transfer the seedlings to individual pots when they have 2-4 true leaves. Seedlings growth is slow to moderate, growing a maximum of about one inch per month. The seedlings are prone to attacks by spider mites; combat this pest with repeated sprayings of horticultural oil.

Growing from Cuttings: I have never grown this plant from cuttings.

Growth in the Garden: This species of ‘ahakea (I have not grown any other) is a challenge in the garden. First, the plant grows rather slowly, perhaps, 1-2 feet per year. Second, they are very prone to attack by black twig borers. Fortunately, because the small tree branches profusely when planted in full sun (in shade, they do not put out many new branches and rarely produce flowers/fruits), these attacks normally do not kill the plant. The best defense against the borers is just enough watering to avoid drought-stress (but don’t overwater or your ‘ahakea may die from a root fungal infection) and prompt pruning of attacked branches. Third, ‘ahakea are susceptible to root mealybugs that can quickly kill them. Inspect the tree’s base and just under the soil surface regularly for mealybugs or the ants that often tend and protect them. Refer to Enemies in the Garden for combating these pests. On the good side, ‘ahakea begin flowering at a very small size – sometimes while they are still ten inches tall in dibble tubes! Provided you have a male and female plant growing together, you should be able to start collecting fruit within two or three years; valuable insurance if you later lose the parent plant(s).

Diseases & Pests: see above

Ā ā Ē ē Ī ī Ō ō Ū ū