110 TREE ANCESTORS 



beams grew in Miocene Europe, and nearly every country on that 

 continent has contributed its records, although there appears to 

 have been a massing of forms in southeastern Europe in the various 

 states and crown lands that formerly constituted the Austrian 

 empire. 



The Phocene records include 7 or 8 forms of central and southern 

 Europe. That North America has furnished no Pliocene horn- 

 beams as yet, is due to the almost complete absence of suitable 

 Pliocene deposits. That hornbeams were present at that time is 

 proved by their presence in the preceding Miocene and succeed- 

 ing Pleistocene deposits. Several of the existing hornbeams appear 

 during Pleistocene interglacial periods, in regions where they are 

 still found. Thus Carpinus hetulus and Carpinus orientalis are 

 recorded from the Pleistocene of central and southern Europe, and 

 our American hornbeam has been found fossil in the Pleistocene 

 of Maryland, North Carolina, Georgia and Alabama. 



THE HOP HORNBEAM 



The hop hornbeam is much like the true hornbeam in appear- 

 ance and habit, but frequents better drained and aerated soils, 

 and is less northern in its range. The most obvious difference 

 between the two trees is in the seed bearing catkins, which in the 

 hop hornbeam are lax and terminal, with the bracts and bractlets 

 united to form a sac-Hke envelope to each flower, and these by 

 midsummer have enlarged to form an imbricated green cone-like 

 affair superficially resembhng a hop blossom — hence the common 

 name of the tree. 



The scientific name, Ostrya, was the classical name of the south 

 European tree. The existing species are few in number and com- 

 prise a very restricted form confined to the canon of the Colorado 

 River in northern Arizona ; a similarly restricted tree in Japan and 

 eastern China; the common hop hornbeam of southern Europe, 

 Algiers and Asia Minor; and the common American tree, often 

 called ironwood because of its hard close grained wood. The last 

 is found from the Gulf of St. Lawrence to Dakota and southward 

 to northern Florida and eastern Texas, reappearing in the uplands 



