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the best all-around trees in most situations. This report will 

 concern itself exclusively with the eucalypts. 



THE EUCALYPTS. 



The genus Eucalyptus belongs to the Myrtle family, the 

 Myrtaceae, to which family also belong the native ohia lehua 

 (Metrosideros polymorpha) and the introduced Java plum (Eu- 

 genia jambolana). The genus Eucalyptus includes about 200 

 different species, but the specific differences are frequently 

 slight, and are in many cases based on the structure of the 

 stamen of the flower, and especially of the anther. In many 

 cases, too, the different species grade into each other so imper- 

 ceptibly that it is necessary to have not only the flowers and fruit 

 but also the leaves, bark, and wood of a tree to determine the 

 species to which it belongs. No attempt will be made in the 

 present report to give a botanical description of any of the trees. 



The various species of eucalypts differ from each other not 

 only in size and form but also in their physical and climatic re- 

 quirements of moisture, temperature, soil, etc. Many eucalypts 

 are straight, cylindrical, and clear of branches for a great height, 

 while others are crooked, forked and branchy. The wood of 

 some trees is soft and brittle, while that of others is hard and 

 tough and very durable. Some eucalypts can thrive on poor 

 soils and can stand much drought, while others require rich, 

 moist soils and plenty of rainfall. By a judicious selection it is 

 thus possible to choose species of eucalypts suitable to almost 

 any situation in Hawaii and fit for almost any use to which wood 

 is put. 



PHYSICAL REQUIREMENTS. 



There are two main natural factors which determine the pos- 

 sibility of introducing eucalypts in any new region namely, (a) 

 climate, including temperature, precipitation and wind, and (b) 

 soil. 



Climate. 



The native home of the valuable eucalypts is in the warmer 

 portion of Australia and a few of the adjoining islands. The 

 question of hardiness to frost is of paramount importance to the 

 growing of Eucalyptus on the continental United States, because 

 the range of the tree is there determined by its ability to endure 

 cold. In Hawaii, however, the question of frost hardiness is not 



