68 OUTLINE OF PLANT GEOGRAPHY 



(Juglans regia), Pterocarya, sweet gum (Liquidambar), honey- 

 locust (Gleditschia), and plane-tree (Platanus orientalis) are all 

 more nearly related to North American and Chinese trees, than 

 to those of Europe. In the same category are showy rhododendrons 

 and azaleas. All of these may be considered as relics of the ancient 

 Tertiary flora, which became extinct in Europe. 



In the Lebanon range of Palestine occur the famous cedars of 

 Lebanon, closely related to the Atlas cedar, already referred to. 



The higher mountains harbor an extensive alpine flora, many 

 species being the same as those of the Alps, but with a large element 

 of peculiar species. 



The interior of Asia is a barren region with an intensely con- 

 tinental climate and meagre rainfall, so that much of it is quite 

 unfitted for human habitation, and indeed is still unexplored. 

 From the Caspian Sea to China, and from the Himalayas to the 

 Altai, the country is largely barren mountains and desert uplands. 

 For the most part it is treeless, and vast stretches are absolutely 

 bare of any vegetation. Where conditions allow a meagre growth 

 of stunted shrubs, they are mostly salt-bush, wormwood, and 

 similar desert species. 



In the less arid regions, especially in the western portion, there 

 is a brief display of herbaceous plants in the spring. Among these 

 are some fine bulbous plants, tulips, fritillaries, iris, and others 

 which soon ripen their seeds, die down and remain dormant for 

 most of the year. 



Southward, however, following the great Himalayan range, 

 there is developed an extremely rich temperate flora, which links 

 that of the Mediterranean with temperate China and Japan. 



The Himalayan Regions 



The great Himalayan region constitutes one of the most impor- 

 tant botanical areas of the world. This loftiest of all mountain 

 ranges is a link between the Mediterranean lands and eastern 

 Asia, and the flora is a remarkable mingling of types belonging 

 to both regions. 



The lower elevations of the Himalaya, rising from the great 

 Indian plain, have a truly tropical flora made up mostly of strictly 

 Indian types; but above the tropical belt there are successive 



