CONIFERALES 231 



According to Engler, in 1926,'^^ there were 40 genera, with about 

 400 species, in the Coniferales. Engler's previous account, in 1889, 

 listed 34 genera, with about 350 species. Some of the additional 

 genera and species are due to discovery and part to the splitting of 

 those already known. 



Writers have made as many as 70 species in the genus Taxus; 

 Engler makes only one. Although we prefer Engler's account, it 

 would seem that forms as different from Taxus haccata as the T. 

 canadensis, of the eastern United States, and T. brevifolia, of the 

 western United States, should be recognized as good species. 



From the first list it will be noted that Pinus, Podocarpus, and 

 Jnniperus are the largest genera, and that they also have wide 

 geographic distribution. Nine of the 39 genera are monotypic and 

 restricted in distribution, while four more are almost monotypic, 

 each having only 2 species. 



geographic distribution 



Whatever uncertainty and difference of opinion there may be in 

 grouping genera into families and in arranging the genera in a family, 

 there can be no difference of opinion in regard to geographic dis- 

 tribution. The record may be incomplete, but there can be no other 

 uncertainty. 



In the cycads, not a single one of the nine genera is common to 

 the Eastern and Western hemispheres. All of the western genera are 

 north of the Equator, except Zamia, which extends from Florida to 

 ChiH; and all of the eastern genera are south of the Equator, except 

 Cycas, which extends from AustraHa to Japan. 



In the Coniferales many genera are common to the Eastern and 

 Western hemispheres, but the proportion of genera crossing the 

 Equator is no greater than in the cycads. In the cycads more than 

 half of the genera are south of the Equator; in the conifers, more 

 than half are north. 



The Podocarpaceae, Taxodiaceae, and Cupressaceae have genera 

 in both Northern and Southern hemispheres. All of the Abietaceae, 

 except a species of Pinus in the Sunday Islands, are north of the 

 Equator. The Araucariaceae and most of the Podocarpaceae belong 

 to the Southern Hemisphere. 



