226 EDWARD W. BERRY 



The fruits unmistakably indicate the genera — those of the 

 hickory have smooth shells and a husk which splits more or less, 

 the walnuts and butternuts have a very rugose surface and an 

 entire husk, while Engelhardtia, Oreomunnea, and Pterocarya have 

 small compound winged fruits. The leaves are always compound, 

 and may be distinguished from those of the ash by being alter- 

 nately arranged instead of opposite. There are numerous other 

 details which enable the student to distinguish between the leaves 

 of the different genera and species. It will be convenient to 

 take up each genus separately and describe something of its 

 present range and such portion of its geologic history as is known. 



THE GENUS HICORIA 



The hickories are now referred to the genus Hicoria, proposed 

 by Rafinesque in 1808, although many systematists, especially 

 in the old world, still use the name Carya proposed by Nuttall 

 in 1818 and universally used until about twenty years ago. 



The hickories occupy a unique economic position, for while 

 the consumption of this wood is less in quantity than that of 

 some of the other hardwoods such as white oak or yellow poplar, 

 or of various coniferous trees like the cypress or the pines, it 

 shares with the black walnut the distinction of being the most 

 costly American wood . Hickory, while not remarkable for beauty 

 of color or of grain, will probably be the most difficult wood to 

 replace when the approaching shortage becomes more acute, 

 since it combines weight, hardness, stiffness, strength and tough- 

 ness to a degree unequaled among commercial woods. The 

 Forest Service estimates that the consumption of hickory for 

 lumber, spokes, tool-handles, rims, shafts, sucker rods, etc., 

 amounted to 450,000,000 board feet during 1908, exclusive of 

 the large amount used as fuel, estimated at about 1,000,000 

 cords — for hickory is also the best American fuel wood. 



The genus Hicoria is entirely confined to North America in 

 the existing flora, more particularly to the eastern United States, 

 although there is an indigenous species in Mexico {Hicoria mexi- 

 cana), and three or four other species reach their northern limit 

 of growth beyond the Great Lakes in Eastern Canada. 



