THE WAY IN WHICH NEW PLANTS ARISE 133 



horse radish, and put in moist sand or soil. Stems 

 and leaves will be seen to appear after a time. The 

 ability to replace the other members of the plant 

 by the root is not very common. It is shared, how- 

 ever, by beech, cherry, poplar, and some coniferous 

 trees. 



183. Structures used hy 2^^ants as means of vege- 

 ^tative reproduction. — Plants have many devices by 

 which portions of the roots, stems, and leaves take 

 on special forms and become separated from the 

 parent plant in a manner which allows them to form 

 a new individual. Chief among these structures are 

 bulbs (see § 167), hidhils, tubers, offsets, stolons, besides 

 many special forms. 



184. Tubers. — -A tuber consists of a portion of 

 an underground stem which serves as a storehouse 

 for surplus food, and which is capable of reproduc- 

 ing the plant by the growth of its buds, which are 

 usually several in number. Examine the base of a 

 vigorous potato stem by digging away the soil. Be- 

 sides the roots will be found numbers of thickened 

 stems or potatoes. Note the " eyes," or buds, on 

 the surface. Are they most abundant on the end 

 toward the main stem or the apical end ? 



