Economic Woods of Hawaii 699 



seven or eight feet in diameter, and long horizontal branches. 

 Under these conditions the crown is a beautiful symmetrical dome, 

 rising from the ground to a height of forty feet. In the dense rain- 

 forest, particularly in the island of Hawaii, the koa has an entirely 

 different growth-form. The trunk is very tall, straight, and un- 

 branched to a height of forty feet above the forest floor. A 

 relatively small crown is developed at the summit of this beautiful 

 gray colimin. The bark may be either smooth or very scaly. 

 In early times the "big koa" was abundant, and many trees at- 

 tained heights of eighty or ninety feet. These largest trees were 

 used by the natives for their war-canoes and huge carved idols, 

 and later by the whites for structural timber and cabinet wood 

 so that today there are few of these veterans standing. 



The koa foliage is thin and diffuse, and crowded at the ends of 

 the branches. The interior of the tree is bare, and one can readily 

 see the entire framework through the spotty and diaphanous super- 

 ficial drapery of foliage. The juvenile foliage, both in the seed- 

 lings and in the young twigs of old trees, is the typical bipinnate 

 mimosoid leaf, with twelve to fifteen pairs of crowded leaflets. 

 The true leaves, however, rapidly pass into the phyllodia; the 

 petioles become expanded, flattened, and sickle-shaped. The 

 mature phyllodium is four to six inches long and half an inch 

 wide, thin coriaceous, very smooth, and longitudinally striate with 

 fine parallel veins. The floral peduncles are solitary or clustered 

 in the axils; each bears a globular head of minute, closely packed 

 white florets. The pod is flat, brown, four inches long, with about 

 a dozen dark brown seeds. 



The range of the koa is considerable — from near sea-level up to 

 5,500 feet — and from hydrophytic to semi-arid habitats. It pos- 

 sesses marked adaptability, but reaches its finest development and 

 largest stands in mesophytic-hydrophytic districts. Although its 

 thin canopy of phyllodia indicates zerophytic adaptations, it is 

 not a tree of the strictly arid lands, and grows with evidence reluc- 

 tance under desert conditions. 



The koa timber is undoubtedly the most valuable wood which 

 the islands now possess. It is typically a rich golden brown, vary- 

 ing through a series of tints and grains, from a straight-grained, 

 rather commonplace "piney" yellow, through to a very hand- 

 some, distinctive, dark mahogany-red, curly-grained type. This 

 latter is the rarest and most highly prized, and is the kind used 



