43 
The Vegetation of Japan. 
The characteristics of the flora of Japan in general are first 
the abundance of species and varieties, secondly, the presence of a 
large number of endemic species, thirdly, the proportion of woody 
plants is remarkably high, and lastly, the presence of tropical and 
sub-tropical elements throughout the country. Even in Yezo, the 
large island of North Japan, are found many representatives of 
southern floras, such as Picrasma, Vitex, Rhus, Hydrangea, 
Lespedeza, Phellodendron, Aralia, Magnolia, and others growing 
together with representatives of the cold flora. In the northern 
parts of Honto, SEsculus, Zanthoxylon, Ardisia, Elceagnus, Smilax, 
and Camellia are often seen. The same or closely allied species 
have been found in the tertiary strata of the north of Eastern Asia. 
Probably in the middle of the tertiary period, even Saghalien had 
a much warmer climate, for at that time Ginkgo, Biota, Sequoia, 
and Nilssonia grew there. When, towards the end of the tertiary 
period, the greater part of the northern hemisphere was covered 
with ice, the main island of Japan seems to have suffered very 
little. Perhaps since the end of the glacial period and the change 
of climate in the middle diluvial age, Japan has maintained a fairly 
warm temperature, enabling many plants of warmer climates to 
survive, while in Saghalien the temperature has been very low, 
so that this island is unfavourable to plants of the warm temperate 
region. The arctic plants once compelled by the cold climate of 
the glacial period to come down southward were consequently left 
behind when the climate became warmer, but only persist on the 
summits of the high mountains. 
Starting with the flora established in the tertiary period, the 
migration of arctic plants towards the south and of tropical plants 
towards the north has caused the present flora to be very complex. 
The connexion of the country with the northern, north-eastern, 
south-eastern, and southern parts of the Asiatic continent made 
paths for arctic and tropical plants into Japan. The interruptions 
between the various islands are bridged over to some extent by the 
currents and wind. The introduction of seeds might not have been 
successful, if the conditions of climate and soil had not been so 
favourable. Evergreen trees and shrubs and many other tropical 
plants found their way by degrees towards the north, and became 
acclimatized—so we may presume—to the colder winter night and 
contented with comparatively high temperature during the day, 
and above all the warm and moist atmosphere during the summer, 
when they can obtain their vital requisites. Those which came 
