Monday, December 22, 2008

Koa in the Mist

This past weekend I spent a frosty Hawaiian winter solstice with the Moku Loa chapter of Sierra Club while on an overnight camping trip at Keanakolu cabins along historic Mana Road on the slopes Mauna Kea. By night there were clear skies filled with billions of stars and a bright mohalu crescent moon; by day, several trails yielded endless opportunities to explore the native flora of the cloud forest.

The dominant tree in this area is the majestic koa (Acacia koa), and in these old-growth forests the trees are over a hundred feet high. As you can see in the above photo, many have developed into the twisted wild forms that make bonsai practitioners shiver and sigh with delight.

Abundant and perhaps apropos for the Christmas season was native Hawaiian mistletoe, hulumoa, an unusual, primitive-looking parasitic plant that lives on koa.

Many a suburban gardener would love to plant a koa tree in the backyard, however, seeing these specimens in the cool, misty upland pastures reminded me that dwarf koa, or koai’a, is probably a better choice for our human-inhabited, drier lowland landscapes.

Koai’a (Acacia koaia) looks like koa but has longer seed pods and a lower, more rounded shape only 15 to 25 feet high; it does well in hot, dry areas. Koa roots tend to send out suckers, but koai’a grows more slowly and is not as aggressive. Unlike regular koa, koai’a is drought tolerant and can tolerate a fair amount of wind and salt.

Note how the crescent-shaped koa "leaves" (actually phyllodes) compare with the pink feather-like leaves of nonnative eucalyptus – quite a difference.

Recently I was impressed with some striking specimens of koai’a in the Waimea Nature Center, a native garden maintained by the community and the Waimea Outdoor Circle. These plantings are an excellent example of how to utilize the distinctive look of koa in residential yards and landscaped areas intended for public recreation.

On the internet, there’s lots of info on growing koa and koai’a.

If you’d like an overview on what the University of Hawaii is doing to save our native forests, click here.

To learn how to propagate koa, click here.

Also, here’s a few superb books to consult:

Growing Koa: A Hawaiian Legacy Tree, by Craig Elevitch and Kim Wilkinson

Growing Native Hawaiian Plants, by Heidi Leianuenue Bornhorst


Anonymous said...

Interesting article . Nice photos!

Merry Christmas, Royce

Anonymous said...

Aloha Janice,

Great photos of koa. Your readers might also want to take a look at the chapter on koa in the book "Traditional Trees of Pacific Islands." It's on line at

Merry Christmas,
J. B.

Anonymous said...

Aloha Janice,

Also people might be interested in reading Scot Nelson's article on the Hawaiian Mistletoes. See his Plant Disease of the Week series at URL:
and scroll down to No. 14.

J. B.

Janice said...

Thanks for the tips, J.B.! Mele Kalikimaka to you and yours...

Anonymous said...

I thought of going on that outing, but the usual holiday stress made it too difficult to make plans. I was busy exploring new areas around Kulani/Keauhou anyhoo. Never enough time...

Sad to see that koa standing all alone in the grass desert. :(

There are a few places where koa are doing well in Hilo, particularly around Kaumana. There would be more around if people were more interested in planting something other than the usual weedy junk that infests town. Even the University is full of alien trees. :/ The place next door to my office has some koa in the landscaping though, and it'll be interesting to see how they develop. I don't think they've tried koaia yet.


Janice said...

Brooks, you might also be interested in reading Alan McNarie's blog on "Koa and the BioFuel Bonanza" at this URL: