456 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



which includes the bluegrasses. The stems grow in large tufts 

 along steep banks. The young stems and flowering shoots are not 

 particularly unusual but the old stems elongate to as much as 10 

 or 15 feet, lose their blades, and hang down the bank in long green 

 rushlike masses that are very striking in appearance. 



The forest trees comprise a gi-eat many species. It is astonishing 

 how many of these species, and in fact species of plants in general,- 

 have been given Hawaiian names by the early inhabitants. Only a 

 few are of sufficient importance to be mentioned here. The com- 

 monest tree on the islands is the ohia or ohia lehua {Metrosideros 

 jJolymorpha) a member of the myrtle family, having a very wide 

 altitudinal range and growing under a great variety of conditions. 

 In size it varies from a mere shrub at high altitudes, to a giant for- 

 est tree in the middle forest zone. The tree has white furrowed 

 bark like that of our white oak and beautiful scarlet flowers with 

 numerous protruding stamens. The wood is hard and durable, and 

 is used for many purposes, including paving blocks and railroad 

 ties. 



Another forest tree is the koa {Acacia koa), important because 

 of its abundance and because of its economic value. Next to the 

 ohia it is the most numerous among the larger trees, and is widely 

 distributed throughout the islands. When growing in the open the 

 koa forms a comparatively low widely spreading tree with a thick 

 short trunk. But wiien growing in the rain forest among other 

 trees it forms tall shapely trunks 40 or 50 feet to the branches. 

 The wood is used in cabinetwork and is becoming familiar to Amer- 

 icans through its use for ukuleles, the mandolinlike musical instru- 

 ments now so popular. The foliage is interesting because of its 

 polymorphism. On the young trees or on vigorous shoots of old 

 trees the leaves are twice pinnate, much like those of our honey 

 locust, but have laterally compressed or flattened petioles. The nor- 

 mal mature foliage, however, consists of these flattened petioles or 

 X)hyllodea, the remainder of the leaf not developing. 



Another species of koa {Acacia koaia) is found in the drier re- 

 gions of the southern islands. 



The traveler is certain to inquire concerning a common tree that 

 attracts attention because of its peculiar light or olive green foliage 

 that is in marked contrast to the prevailing green of the forests. 

 This is the kukui {Alem^tes .moluccana) ^ found widely distributed 

 in the islands at lower altitudes up to about 2,000 feet. The leaves 

 remind one of those of the castor oil plant, which the young kukui 

 plants closely resemble. The nuts of the kukui are rich in oil, 

 which is an important article of commerce. The species has a w^ide 

 range in Polynesia and tropical Asia. In the English colonies it 

 is called candleberry or candlenut tree. 



