112 TREE ANCESTORS 



distinguishing Ostrya leaves from those of Carpinus, under which 

 name perhaps some true fossil species of hop hornbeam may be 

 masquerading, since the characteristic winged fruits of the hop 

 hornbeam have been found as far back as the early Tertiary. The 

 oldest of these is from the lower Eocene of Texas. Shghtly younger 

 are similar remains described by Heer from western Greenland. 

 Two species have been recognized in the Oligocene of France and 

 no less than 9 species are recorded from the Miocene and Pliocene 

 of Europe and North America. These occur in New Jersey and 

 in the lake basin of Florissant in Colorado in this country; and 

 in France, Baden, Germany, Croatia, and Styria in Europe. The 

 known Pleistocene records are limited to the occurrence of our 

 existing American species in Japan, Ontario and Alabama. 



THE ALDER 



"But here will sigh thine alder tree." 



— Tennyson. 



Alders are not remarkable for either size or longevity, neverthe- 

 less they were associated with the early days of the Anglo-Saxon 

 race and have taken their place in its poetry and folk lore. The 

 above quotation suggests something larger than the small shrubby 

 "alders by the brook" that Bryant has immortalized, and as a 

 matter of fact several of the alders reach a height of 40 to 50 feet, 

 and one — the white alder, Alnus rhombifolia, of the Cascade and 

 Sierra Nevadas — reaches a height of 80 feet and has a tall straight 

 trunk 2 or 3 feet in diameter. Most of the alders, however, have a 

 distinctly shrubby appearance even when 50 feet tall. Alder wood 

 is dense, but soft and brittle, and largely sapwood, hence it is of 

 slight commercial importance, although the common European, 

 Algierian and Asiatic Alnus glutinosa is sometimes a timber tree 

 because of the durability of its wood under water, but even it is 

 of relatively sHght importance. The astringent bark and cones 

 are also used to some slight extent in tanning and medicine. 



The scientific name, Alnus, is the classical name of the alder. 

 There are about 20 existing forms, half of which occur in the West- 

 em Hemisphere, all but 2 or 3 attaining to the stature of trees. 



