66 



ELEMENTS 01- STRUCTURAL BOTANY. 



Potato plaut, and examine the underground portion 

 (Fig 99). It is not improbable that you will regard 

 the ■whole as a mass of roots, but a very little trouble 

 vvil; undeceive you. Many of the fibres are unciues 

 tionably roots, but an inspection of those having pota- 

 toes at the ends of them will show you that they are 

 quite different from those which have not. The former 

 wih be found to be furnished with little scales, answer- 

 ing to leaves, each with a minute bui in the axil ; and 



the potatoes them- 

 selves exhibit buds of 

 the same kind. The 

 potato, in short, is 

 only Hit swollen end of 

 on vndenjround stem 

 Such swollen ex- 

 tremities are known 



as tubers, whilst clie 



Fig. ICO. — —'^ 



underground stem is called a rootstock, or rhizome, and 

 may always be distinguished from a true root by the 

 presence of buds. The Solomon's Seal and Toothwort 

 is Canadian woods, and the Canada Thistle, are com- 

 mon instances of plants producing these stems. Fig. 

 lOO shows a -rhizome. 



92. Take now an Onion, and compare it with a 

 Potato. You will not find any such outside appear- 

 ances upon the former as are presented by the latter. 

 The Onion is smooth, and has no buds upon its surface. 

 From the under side there spring roots, and this cir- 

 cumstance will probably suggest that the Onion must 

 be a stem of some sort. Cut the Onion through from 

 top to bottom (Fi-. 101). It will then be seen to bo 



