40 PLANT LIFE ON THE FARM. 
“tiller” up from the base of the stems of the wheat 
originate as buds from the axils of the lower leaves, while 
the upper ones are destitute of them. When a tree is 
“‘pollarded,” a large crop of buds makes its appearance ; 
and the multiplication of some weeds, like thistles and 
bindweed, after their stocks have been cut through with 
the hoe at insufficient depths below the surface, is due to 
a like formation of buds. 
The tuber of the potato may be mentioned under this 
heading. Though commonly called a root, because it 
happens to grow below-ground, it is clearly a stem, 
because it is provided with ‘‘ eyes,” which eyes, as may 
be seen when the tuber begins to sprout, are nothing but 
buds. A tuber, then, is a portion of the stem of the 
plant, in which the tissues become thickened and filled 
with nutritive matter (in this case starch), which is pro- 
vided with buds, and which, when once fully formed, is 
separated from the parent haulm or stem by the gradual 
decay and death of the latter. A tuber of this kind ful- 
fils in the economy of the plant much the same purpose 
as the seed; and hence the term “seed potato,” though 
far from correct in a technical sense, conveys, neverthe- 
less, a not wholly incorrect idea. 
A “bulb,” such as that of an onion, is a portion of 
the stem modified for the same purposes as the tuber ; 
but whereas in a tuber the stem itself is swollen, and the 
leaves reduced to the merest scales, in a bulb the condi- 
tions are reversed : the fleshy scales of an onion bulb are 
really the bases of the leaves, as any one may see who 
will examine an onion in growth, while the stem itself is 
reduced to a mere, flat, and not very thick plate, from 
the sides of which emerge the leaves. The term kalb, as 
applied to such a root as the turnip, is inaccurate. 
These illustrations, taken from plants most familiar to 
the cultivator, will suffice to show the general character 
of the stem and its subdivisions, and will indicate the 
