HORNBEAM, HAZEL, BIRCH AND ALDER 109 



not a stately tree, rarely reaching a height of 40 feet, and generally 

 bushy in appearance, with a short fluted trunk, long slender irregu- 

 larly spreading branches and light brownish-grey bark. It is dis- 

 tinctly mesophytic in habitat and most frequently found along 

 stream or swamp borders, and reaches its largest size on the west- 

 em slopes of the southern Alleghanies and in Arkansas and eastern 

 Texas, dying out westward in the river valleys of the prairie States 

 and reappearing in the mountains of southern Mexico and Central 

 America. 



The number of known fossil species of hornbeam considerably 

 exceeds the number of species now living, and their geographical 

 range was, of course, greater. The hornbeam is not certainly 

 known as early as the Upper Cretaceous, although leaves from 

 the late Cretaceous of western Greenland were described by Heer 

 under the name of Carpinites microphyllus, and these may well 

 represent the earhest known hornbeam, although they are not 

 especially convincing. That the hornbeams originated in the 

 North seems reasonable because, with the exception of two sup- 

 posed species in the early Eocene of France, the most abundant 

 Eocene form is the so-called Carpimis grandis which occurs on 

 the Island of Sachalin of the eastern Asiatic coast, in Alaska over 

 2000 miles from the nearest existing occurrence, in British Colum- 

 bia, in the lignite deposit of Brandon, Vermont, in western Green- 

 land and Spitzbergen — both the last over 1000 miles north of the 

 existing limits of the genus. Such a distribution would seemingly 

 be impossible if the ancestral forms had originated in low latitudes. 



The hornbeam is apparently absent from the extensive Eocene 

 floras of the western United States although discovery may at 

 any time disclose it in that region where it might be expected to 

 have been present. Nor has it been found in the warmer floras of 

 our southeastern States. In succeeding Ohgocene times several 

 hornbeams have been found in Russia, Germany, Italy and France. 



The Miocene species were more numerous than the existing forms, 

 numbering about a score. They occur in North America from 

 Virginia to Colorado, Nevada and Oregon; and in the Old World 

 from Japan and Siberia to Spain. No less than 17 diflferent horn- 



