108 



TREE ANCESfORS 



are frequently used for fodder. Its resemblance to the elm is 

 superficial and is based on the leaf arrangement and the smooth 

 greyish bark. 



The pollen bearing and seed bearing flowers are in separate 

 catkins and those of the latter, which are lax and bracteate, de- 

 velop into small ribbed nutlets while the bracts are enlarging to 

 form the three lobed and normally serrately margined wings. 



Fig. 21. Sketch Map Showing the Existing Range and Fossil 

 ocurrences of the hornbeam 



The hornbeams are confined to the Northern Hemisphere and have 

 about a dozen existing species, found in America from Quebec to 

 the Central American highlands, and in Eurasia from Sweden to 

 southern Europe, Asia Minor, the temperate Himalayas, central 

 China and Japan. 



Of the dozen existing species, only one — the hornbeam or blue 

 beech, Carpimis caroliniana, is found in North America. This is 



