2 



THE AMERICAN BOTANIST. 



in woody stems is soon cutinized, or covered with cork, a 

 substance having the power of resisting entrance of water. 

 It is this outer bark, which imparts to shrubs and trees 

 their peculiar specific color, varying in the young state, 

 from green or yellowish, to grey, brown, orange, or brilli- 

 ant red. In late winter, the observer, as he passes along 

 in the rapid flight of a railway train, will note that 

 willow twigs are becoming golden, and the red maple 

 beautifully ruddy. They are feeling the pulse of re-awak- 

 ening life. 



When this tissue takes an unusual development, as in 

 cork oak, it forms the commercial cork applied to so 

 many useful purposes. Indeed, it would seem, like rubber, 

 absolutely indispensable to civilization, Cork also forms 

 the beautiful, exfoliating layers of birch bark. Every vis- 

 itor to the White Mountains or the Adirondacks knows 

 how these successive layers may be peeled off till one comes 

 to a beautiful olive green surface beyond which it is not 

 safe to go. Indeed, the peeling as practiced, is in time 

 ruinous to the tree. 



Says Goodale, ''Each yearly addition to the inner sur- 

 face of the bark is seldom plainly distinguishable from 

 those which have preceded it, and hence we cannot deter- 

 mine positively the age of an old tree by the layers of its 

 inner bark. The bast fibres of a single year often cling to- 

 gether in a striking manner, forming bands or strips of 

 considerable length, and in a few cases, notably that of 

 Daphne Lagetta, there are fine meshes between the fibres, 

 so that the inner bark seems to be composed of delicate 

 fibres." This is the familiar lace bark of museums. 



Among the functions of cork is to heal the smaller 

 wounds of plants. Originally smooth, the bark in time 

 becomes furrowed or wrinkled by the expansion of the 

 tree, and this in a peculiar way for each kind of tree. 

 How different is the surface of the ash, say, from that of 

 maple or elm, or any of these from each other ! We may 

 remark in a general way, that the bark breaks into those 

 distinctive patterns as the result of continual expansion. 



