104 THE AMERICAN BOTANIST 



species of tree throws off its bark is a method all its own. 

 The differences is often considerable even in the same family. 

 Witness the rough heavy bark of the rock oak as compared 

 with the thinner smoother exterior of the white oak. The 

 bark of the ironwood is fine and stringy and the older the tree 

 grows the finer this bark becomes, while that of the button- 

 wood comes off in thin flakes and the tree usually looks as if 

 white-washed. The curly papery bark of the birches is well 

 known. That of the black and yellow birches contains so much 

 oil that experienced campers always use it on rainy days in 

 kindling a fire. The day must be wet indeed when bark from 

 the under side of a leaning birch tree will not burn. Touch 

 a match to this papery bark on a standing tree some day next 

 winter when the ground is covered with snow and danger 

 from fires out of the question. The orange colored flame will 

 mount up the bole of the tree as long as there is anything to 

 feed upon and form a most beautiful picture in the quiet 

 woods. The burning of this outer bark does not injure the 

 tree in the least, in fact all exogenous trees — those that grow 

 by annual additions to the outer layer of wood — have some 

 provision made for getting rid of this outer, bark. 



Not only have the trees their own particular kind of bark, 

 but they have also separate ways of disposing their trunks 

 and branches. When in the forest with numerous other spe- 

 cies, they must struggle up as best they can to the light and 

 air over head, but when left to themselves with no competitors 

 near, they assume their own peculiar shapes. Notice how the 

 elm grows upward in a graceful fan shaped or plume like 

 head, while the lombardy poplar with branches growing in the 

 same general direction resembles nothing so much as a worn 

 out broom, with each separate twig possessed with a desire to 

 point as near the meridian as possible. How this stiff and 

 awkward poplar ever came to be cultivated in dooryards when 

 other trees were to be had, seems a mystery. We are inclined 



