LUMBER TREES 117 



development of which its exterior appearance 

 gives but faint suggestion. 



It appears that there is full warrant for the 

 belief that the modern flora originated in the 

 Northern Hemisphere, and probably in the 

 region of the North Pole. During the so-called 

 Mesozoic Age, the conditions of the Northern 

 Hemisphere were those that would nowadays be 

 described as tropical or subtropical. There were 

 palms growing in Europe and in Alaska, and 

 such species as the sequoia, the plane trees, 

 maples, and magnolias grew even at a relatively 

 late period as far north as the seventieth degree 

 of latitude. Remains of conifers have been found 

 within nine degrees of the pole itself; remains of 

 palms in Alaska coal measures, and of the 

 sassafras along the western coast. 



At this early period the flora of the entire 

 Northern Hemisphere was, as regards its trees, 

 essentially comparable to the existing flora of 

 America to-day. 



There were oaks and beeches scarcely dis- 

 tinguishable from existing species. 



There were birches and planes and willows 

 closely related to the living species known as 

 Salicc Candida. 



There were laurels not unlike their modern 

 representatives, the sassafras and cinnamon tree, 



