4 FOREST FLORA OF JAPAN. 



A further examination of the trees of the two countries shows that, although the Japan- 

 Manchurian region possesses more arborescent species than eastern America, the silva of the 

 latter is much richer in genera, one hundred and thirty-four to ninety-nine in Japan- 

 Manchuria. Forty-four genera have arborescent species in the two regions ; forty-five genera 

 with Japanese representatives have none in the flora of eastern America, and thirty-eight 

 genera represented in the American flora do not appear in that of Japan. A few genera, five 

 in eastern America and seven in Japan, are represented by trees in one region and by shrubs 

 only in the other. Of endemic arborescent genera the silva of eastern America contains 

 Asimina, Koeberlinia, Cliftonia, Ungnadia, Robinia, Cladrastis, Pinckneya, Oxydendrum, Mohro- 

 dendron, Sassafras, Planera, Toxylon, Leitneria, Hicoria, and Taxodium, fifteen, while in Japan 

 there are only five, Cercidiphyllum, 1 Trochodendron, Platycarya, Cryptomeria, and Sciadopitys. 



Such a comparison between the silvas of eastern America and Japan is interesting as 

 showing the great number of arborescent species inhabiting four small islands. The signifi- 

 cant comparison, however, if it can ever be made, will be between eastern America, as here 

 limited, and all of eastern Asia from the northern limits of tree-growth to the tropics, and 

 from the eastern rim of the Thibetan plateau to the eastern coast of Japan. This would 

 include Corea, practically an unexplored country botanically, especially the northern portions, 

 and all the mountain ranges of western China, a region which, if it is to be judged from the 

 collections made there in recent years, is far richer in trees than Japan itself. It is impossible 

 to discuss with precision or with much satisfaction the distribution of the ligneous plants of 

 the north temperate zone until more is known of western China and of Corea, where may be 

 sought the home of many plants now spread through eastern China and Japan, and where 

 alone outside the tropics the enterprising and industrious collector may now hope to be 

 rewarded with new forms of ligneous vegetation. 



Travelers in Japan have often insisted on the resemblance between that country and eastern 

 America in the general features of vegetation. But with the exception of Yezo, which is still 

 mostly uninhabited and in a state of nature, and those portions of the other islands which are 

 over 5,000 feet above the level of the ocean, it is difficult to form a sufficiently accurate idea 

 of the general appearance of the original forest-covering of Japan to be able to compare the 

 aspects of its vegetation with those of any other country, for every foot of the lowlands and 

 the mountain valleys of the three southern islands has been cultivated for centuries. And 

 the foothills and low mountains which were once clothed with forests, and could be again, 

 are now covered with coarse herbage, principally Eulalia, and are destitute of trees, except 

 such as have sprung up in sheltered ravines, and have succeeded in escaping the fires which 

 are set every year to burn off the dry grasses. Remoteness, bad roads, and the impossibility 

 of bringing down their timber into the valleys have saved the mountain forests of Japan, 

 which may still be seen, especially between 5,000 and 8,000 feet above the level of the sea, in 

 their natural condition. But these elevated forests are composed of comparatively few species, 

 and if it were not for the plantations of Conifers, which the Japanese for at least twelve 

 centuries, it is said, have been making to supply their workers in wood with material, and for 



1 Since this was written I have received through M. M. L. de Vilniorm of Paris seeds of a Cereidiphyllum gathered in 

 the extreme western part of China. 



