INTRODUCTION xxix 



Gymnanthes, and Hippomane, which are small trees of tropical 

 Florida. In eastern continental Asia woody plants of this family 

 occur in Bridelia, Andrachne, Sauropus, Phyllanthus, Glochidion, 

 Securinega, Breynia, Bischofia, Aporosa, Daphniphyllum, Anti- 

 desma, Microdesmis, Alem"ites, Croton, Blachia, Claoxylum, 

 Acalypha, Alchornea, Mallotus, Macaranga, Homonoia, Endosper- 

 mum, Gelonium, Homolanthus, Erismanthus, Sapium, Sebastiana, 

 and Excoecaria. Nearly all of these are tropical genera which, 

 coming from the south, have obtained a foothold in south-eastern 

 China. Only Andrachne, Croton, and Sebastiana have representa- 

 tives in the two regions. Aleurites, a genus of trees which produce 

 the wood-oil of commerce, is probably the most valuable genus of 

 the family in the two regions. 



BuxACE^. — One species of Pachysandra occurs in each of the 

 two regions ; the other genera of this family in the two regions, 

 Buxus and Sarcococca, are Chinese. 



CoRiARiACE^, a family of a single genus, Coriaria, has a re- 

 presentative in China but not in America. 



Empetrace^. — Empetrum occurs in north-eastern North 

 America and in north-eastern continental Asia, and the other 

 genera of this family, Corema and Ceratiola, are eastern North 

 American, and have no Asiatic representatives. 



ANACARDiACEiE. — In this family, Pistacia, Rhus, and Cotinus 

 are represented in the flora of the two regions. Metopium is 

 American, and Spondias, Mangifera, and Dracontomelum are 

 Chinese. In China, Pistacia chinensis Bunge is a large, widely 

 distributed, and valuable tree, but in the United States Pistacia 

 mexicana H.B.K. has secured only a precarious foothold on the 

 northern bank of the Rio Grande in Texas. Of the members of 

 this family in the two regions Rhus verniciflua Stokes, the Chinese 

 Lacquer tree, is no doubt the most valuable. 



Cyrillace^. — ^This exclusively American family is represented 

 in eastern North America by Cliftonia and Cyrilla. 



AguiFOLiACEiE. — Of this family. Ilex is widely distributed in 

 the two regions, and the monotypic Nemopanthus is east North 

 American. Ilex usually grows to a larger size in China than in 

 eastern North America, but is less northern in its range in the 

 former region where most of the species are evergreen. 



Celastrace^e. — In this family, Celastrus and Evonymus are 

 common to the two regions. Tripterygium, Perrottetia, Micro- 

 tropis, and Elgeodendron are eastern Asiatic and not American, 

 and Pachystima, Maytenus, Crossopetalum, Gyminda, Schaefleria, 



