INTRODUCTION xxxvii 



GooDENiACE^. — A Chinese species of Scaevola is the only woody 

 plant of this family in the two regions. 



Composite. — Iva and Baccharis, of the Atlantic coast region, 

 are the American shrubby representatives of this family, which 

 occurs in China in several species of Blumea and in Pertya. 



It appears, therefore, that 129 natural families are represented 

 in the two regions under consideration ; that of these 92 are common 

 to the two regions, that 12 occur in eastern North America, but not 

 in eastern continental Asia, and that 25 occur in eastern continental 

 Asia and not in eastern North America. Of the 692 genera in the 

 two regions 155 are common to both, while 158 are found in eastern 

 North America and not in eastern continental Asia, and 379 are 

 found in eastern continental Asia and not in eastern North America. 

 Of the tropical genera 76 have reached southern Florida and 89 

 south-eastern China. 



From Mexico the flora of the United States has derived 42 

 genera of the woody plants of Texas. 



It is impossible to form an accurate estimate of the comparative 

 number of species of woody plants in the two regions at this time, 

 but including Crataegus it is probable that the number is as great 

 in eastern North America as in eastern continental Asia. 



C. S. SARGENT 

 Arnold Arboretum 

 July 1913 



