390 Field, Forest, and Wayside Flowers 



of pines and larches. Sometimes the scales form, 

 but remain clinging to one another upon the tree, 

 so that, in the course of years, the trunk becomes 

 covered with large plates of dead tissue, overlap- 

 ping each other like shingles on a roof, and mak- 

 ing what is called ''scale-bark." Such dried-up 

 flakes, clinging together, may be seen partly 

 covering the trunks of old pine-trees. 



The larger roots of the trees are wrapped in corky 

 tissue, just as the trunk and branches are, but in 

 summer the slenderest tips of growing rootlets are 

 not. The chief use of the large roots is to 

 anchor the tree to the spot where it grows. But 

 the work of the little rootlets is to suck up moist- 

 ure and nourishment from the surrounding soil, and 

 if they were sheathed in cork they could not 

 fulfil this office. 



Each rootlet, just above its tiny tip end, is 

 furred over with hairs (Fig, 101), slender and soft, 

 yet tough enough to press in between the grains 

 of close-packed soil, and draw food and drink out 

 of it. 



As winter approaches, these little "root-hairs" 

 shrivel and drop off, and the root-tip from which 

 they sprang becomes enwrapped, like the larger 

 roots, with a layer of cork-cells. So the whole tree, 



