40 PLANT LIFE ON THE FA KM. 



"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 balb, 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 



