30 



The Koa Tree 



By C. S. Judd, Superintendent of Forestry, 



Probably the best known and most popular, for a variety of 

 uses, of all the native Hawaiian trees is the koa. Acacia Koa 

 Gray. It is the largest sized tree in the Hawaiian forest, is very 

 widespread, and next to the ohia lehua is the most common. The 

 koa is found on all the larger islands of the Hawaiian group and 

 adapts itself to a great variety of conditions, although it prefers 

 and grows best on a well drained soil. 



GENUS. 



The koa belongs to the genus Acacia, which boasts of approxi- 

 mately 500 species, which are distributed over the tropical and 

 sub-tropical regions of both worlds, being especially numerous 

 in Africa and Australia. In these islands the genus is repre- 

 sented by three species, one of which has two varieties : 



Acacia Koa, the common species, which is familiar to all. 



Acacia Koa lanaiensis, a smaller tree with shorter, almost 

 straight leaves, found only on the island of Lanai. 



Acacia Koa hazvaiiensis, a tall tree, with very broad leaves 

 which are almost straight, and found only on the island of Ha- 

 waii. 



Acacia Kauaiensis, a large tree, with sickle-shaped, narrow 

 leaves, fiow^ers in panicles or pyramidal loosely-branched clusters, 

 and found only on western Kauai. 



Acacia Koaia, a smaller tree, with very hard wood and gnarled 

 and twisted branches, pods narrower and somewhat curved, leaves 

 stiff and narrow, and found at the lower elevations on the dry 

 portions only of Molokai, Maui, and Hawaii. 



ORIGIN. 



How the koa first came to the Hawaiian Islands is a much 

 mooted question. Its hard, horny seeds do not float in water 

 and are therefore not adapted to dispersal by ocean currents. 

 It does not seem probable that the koa was introduced by human 

 agency, because of the very long time that the tree has been 

 here. This is evidenced by the endemic fauna of birds and in- 

 sects which are quite restricted to or dependent on the koa for 

 their existence and which prove that the host tree is a very an- 

 cient denizen of these islands. The seed of the koa may have 

 been first brought here by birds, and it is not unlikely that the 

 tree found its way to this region by terrestrial immigration over 

 a continent which at one time may have connected this group 

 with Australasia and Indo-Malaysia, but which has since sub- 



