204 BOTANY. [chap. vii. 



extensive pine forests occur. Poplars and birches are 

 also present. Grasses and ling {Galluna vulgaris), also 

 junipers, are amongst the social or gregarious plants 

 that form features in the physiognomy of certain dis- 

 tricts in this zone in northern latitudes. In the 

 southern hemisphere the same zone embraces a few- 

 barren islands. 



The Gold Temperate Zone in the Northern Hemisphere 

 includes England, Northern Prance, Germany, etc. ; the 

 forest trees are all dicotyledons, amongst which conifers 

 predominate j the heaths and grasses are the most con- 

 spicuous of social plants. This region is most favourable 

 for the cultivation of wheat. 



The Warm Temperate Zone includes in Europe the 

 southern flora as far as the Pyrenees, also the mountains 

 of the south of France and the North of Greece, Asia 

 Minor, a zone extending between the Black sea and the 

 Caspian, Northern China, Japan, and a belt in North 

 America are also included. It is sometimes spoken of 

 as the zone of evergreen trees, and includes numerous 

 sub-tropical forms, as laurels, myrtles, figs, vines, etc. 

 The dwarf palm {Chamerops humilis), a small species, is 

 the only European representative of the Palm order. 



The Sub-tropical Zone extends from the tropics to 

 34° north and south latitude, with a mean annual tem- 

 perature ranging between 60° and 70° Fahr., and a 

 summer temperature between 74° and 83° Fahr. In this 

 zone vegetation is green throughout the year. It has 

 been called the region of Myrtacese and Lauracese on 

 account of the predominance of species belonging to 

 these orders. Heaths and their Australian representa- 

 tives, epacrids, are also conspicuous. The arid regions 



