62 PRACTICAL COURSE IN BOTANY 
Make a longitudinal section passing through the central 
portion of the root and extending an inch or two into the 
lower part of the stem. Do you find any sharp line of divi- 
sion between them? Notice the hard, woody axis that runs 
through the center. This is the vascular cylinder and con- 
tains the conducting vessels, the cut ends of which were 
shown in cross section in Fig. 76. 
65. Distinctions between root and stem.— Pull off a 
branch from the stem and one from the root; which comes 
off the more easily’? Examine the points of 
attachment of the two and see why this is so. 
This mode of branching from the central 
axis instead of from the external layers, as 
in the stem, is one marked distinction be- 
tween the structure of the two organs. In 
Fic. 77.—Verti- stems, moreover, branches occur normally 
section of branching above the points of leaf insertion at the 
root, showing the ; i 
branches, n, n, origi- nodes (46), while in the root they tend to 
aes ware sce arrange themselves in straight vertical rows. 
through the cortex, The shoots and cions that often originate 
ous from them are not normal root branches, 
but outgrowths from irregular or adventitious buds, that 
may occur on any part of a plant. The root is not divided 
into nodes like the stem, 
and never bears leaves. 
66. The active part of 
the root.—It is only the 
newest and most delicate 
parts of the root that pro- 
duce hairs and are engaged 
in the active work of absorp- 
tion, the older parts acting 
mainly as carriers. Hence, 
old roots lose much of their 
characteristic structure and eae : 
take on more and moreo! agi, atiwacc 
