CONIFERALES (PINACEAE) 3°! 



eggs; but that actually it produces lo 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 Libocedrus, 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 cormection with the tribes. 



The Abietineae are almost exclusively northern, the dominant 

 genera, distributed throughout the temperate regions of the north- 

 em hemisphere, being Pinus, Abies, Picea, and Larix, genera 

 which include 116 of the 129 species of Abietineae. China con- 

 tains two endemic genera {Pseudolarix 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 eight genera are narrowly restricted in range, and three of them 

 are monot3^ic. If the tribe is at all natural, the distribution indi- 

 cates a former wide extension represented now by thirteen species 

 in eight widely scattered and endemic genera. Five genera (Scia- 

 dopitys, Cunninghamia, Taiwania, Cryptomeria, and Glyptostrobus) 

 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 hem- 

 isphere (Tasmania and Victoria). This distribution seems un- 

 natural 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 



