104 HORTICULTURAL SOCIETY OF NEW YORK. 



tains in Asia Minor and from Austria and the Balkan Penin- 

 sula thrive here. That region has an annual range of 30 to 40° 

 and a January average of 30° or a little below. 



Evergreens from the mountains of North Carolina thrive 

 here. Linville, Xorth Carolina, has 31° January mean, and 

 about 40° annual range. 



Evergreens from Maine, the Adirondacks and ^Michigan 

 thrive here, except a few slightly dislike our warmer periods in 

 winter, alternating with cold, dry northwest winds. In other 

 words, they do not like to be awakened in winter by bright 

 sun and a temperature of 65°. They like steady cold. 



The above applies to regions whose conifers thrive here. 

 Evergreens from the two west coasts do not permanently thrive 

 here. 



The line of 20° annual range passes through Spain, France, 

 England and Norway, and through California, Oregon, Wash- 

 ington and the coast of British Columbia, the southern slope of 

 the Himalayas and southwestern China. 



Isothermal lines and latitude are not a guide to the intro- 

 duction of plants from the two west coasts. The isotherm of 50 

 passes through here and through southern England, Ireland and 

 the State of Washington. 



Prof. W. M. Davis, of Harvard, from whom this map is 

 copied, says that the reason for the small range of temperature 

 along our Pacific coast and the western coast of Europe, and 

 the area of strong range along our eastern coast, and the eastern 

 coast of Asia, is the combined action of ocean currents and the 

 winds, particularly in the control of the distribution of tempera- 

 ture by the winds. 



In temperate latitudes the prevailing course of the winds 

 is almost from west to east. 



The above statements have been made mostly with conif- 

 erous evergreens because they are awake all the year and record 

 the whole climate of their native country and where introduced, 

 except drought. They generally require only a fraction as much 

 water as deciduous trees. 



Deciduous trees and shrubs go to sleep in winter by drop- 

 ping most of their evaporating surface, and if their foliage is 



