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, 
