INTRODUCTION xix 



only eight species occur ; and in eastern America Pine trees are 

 individually larger, more numerous, and more generally distributed 

 than in China. In Picea, China, with its twenty species, has a decided 

 advantage over eastern America, where only three species occur, 

 and in Abies, China, with its nine species, is richer than eastern North 

 America, where there are only two species, and of these one is found 

 only on the highest peaks of the southern Appalachian Mountains. 

 Of Tsuga there are two species in eastern North America and two 

 species in China, but Tsuga canadensis Carr. is a larger tree and 

 much more widely distributed than any of the Chinese species. 

 Larix, on the other hand, is better represented in eastern continental 

 Asia, where it is widely distributed with several species from eastern 

 Siberia to the mountains of Western China, where it sometimes forms 

 large forests, while in eastern America there is a single species con- 

 fined to the north-eastern part of the continent and is a small tree 

 which southward is found only in swamps. Juniperus is represented 

 in China by six species, and in North America by five species ; but 

 none of the Chinese Junipers are as large or as widely distributed as 

 Juniperus virginiana L. ; and none of them produce so valuable wood 

 as that species and /. harhadensis L. Thuya is represented in each 

 region with a single species of about equal importance. In eastern 

 America Taxodium is a large and valuable timber tree widely 

 distributed in the South Atlantic and Gulf regions, while its Asiatic 

 representative, Glyptostrobus, is a small tree confined to the banks 

 of a few streams in south-eastern tropical China. 



TAXACEiE. — In this family the advantage is all with China, 

 with Taxus, Torreya, Cephalotaxus, Gingko, and Podocarpus, 

 while in eastern America it appears with only a single species each 

 of Taxus and Torreya, small trees found only in a few smaU isolated 

 groves in western Florida . 



Gnetace.i;. — Represented in continental Asia by Ephedra 

 and Gnetum, this family does not appear in eastern North America. 



Pandanace^. — One species of Freycinetia and two species of 

 Pandanus represent this Old World family in southern China. 



Palm^. — About the same number of species of Palms are re- 

 ported from the two regions, fourteen species in seven genera in 

 China, and sixteen species in eight genera in eastern North America. 

 The species in the two regions belong to different genera, with the 

 exception of Cocos nucifera L., which is found on all the tropical 

 shores. In eastern North America Palms extend farther north than 

 in China, and some of the dwarf species cover in the southern 

 United States great areas of dry sandy land with almost impene- 



