COXIFKRALES (PINACEAE) 301 



eggs; but that actually it produces 10 to 20 good embryos in as many 

 seeds. 



5. Distribution 



The geographic distribution of Coniferales as a whole is in striking 

 contrast with that of Cycadales, the former belonging to the temperate 

 regions of both northern and southern hemispheres, and the latter 

 belonging to the tropics and subtropics. The Pinaceae are massed 

 chiefly in the northern hemisphere, and there is no crossing of the 

 tropical belt by any genus except Lihocedrus, which extends far into 

 temperate South America by way of the Andes, and reaches Australia 

 through the East Indian region. The main facts of distribution may 

 be stated in connection with the tribes. 



The Abietineae, including more than half the species of Pinaceae, 

 are almost exclusively northern, the dominant genera, distributed 

 throughout the temperate regions of the northern hemisphere, being 

 Pinus, Abies, Picea, and Larix, genera which include 115 of the 129 

 species of Abietineae. China contains two endemic genera (Pseudo- 

 larix and Keteleeria) and North America one {Pseudotsuga); while 

 Tsuga is North American and Asiatic, and Cedrus is Asiatic and North 

 African. Both structure and distribution indicate a very natural 

 group, which forms the chief gymnospermous forest display of the 

 northern hemisphere. 



The Taxodineae are a remarkable group geographically, for all 

 the genera, eight in number, are narrowly restricted in range, and three 

 of them are monotypic. If the tribe is at all natural, the distribution 

 indicates a former wide extension, represented now by thirteen species 

 in eight widely scattered and endemic genera. Four genera {Scia- 

 dopitys, Cunninghamia, Taiwania, and Glyptosirohus) occur only in 

 the China-Japan region; two genera {Sequoia and Taxodium) are 

 found in restricted areas of North America; while the remaining 

 genus {Arthrotaxis) belongs to the southern hemisphere (Tasmania 

 and Victoria). This distribution seems unnatural for a natural 

 tribe, especially when contrasted with the distribution of Abietineae. 



The Cupressineae are almost as remarkable in their distribution 

 as the Taxodineae. Two genera, including more than half the species, 

 range widely through the northern hemisphere, Juniperus belonging 

 to the whole north temperate region, and Cupressus occurring in 



