Exploring the Woodpile 169 



woodpile piecemeal, we may be able to compare 

 the old bark near the base of its trunk with the 

 much younger bark near its branch tips. 



The bark of some trees, as they grow older, 

 changes so greatly in appearance that branches and 

 trunk scarcely seem to belong together. 



A yellow or gray birch, when it is young, can 

 be known at once by the little soft curls of silver 

 bark which cling to its satiny stem. But as the 

 tree grows old, the satin coat, with its curly fringes, 

 is removed by time, so that huge gray birches may 

 be seen in mountain forests with trunks wrapped 

 in rough, deeply-channeled bark, as different as 

 possible from the satin coats still worn by the 

 younger boughs. There is just as great a differ- 

 ence between the flaked gray trunks of the old 

 apple trees and their smooth, olive-colored 

 younger branches. 



On some sticks of the woodpile we shall prob- 

 ably find thorns, for they are borne by several 

 native trees. 



The botanist makes a distinction between a 

 prickle and a thorn. A prickle is attached to the 

 bark only, and comes off when the branch is 

 peeled. But a thorn is a fixture. It has a wooden 

 backbone, and is part of the branch. 



Sometimes, indeed, a thorn is a small branch, 

 stunted and gone wrong, and this has happened 

 because the plant lived in poor soil, lacked mois- 

 ture, or otherwise suffered hardship. Apple and 



