364 



IiJESSOIfS WITH PLANTS 



do not always 



radish, carrot, parsnip, salsify (Fig. 382) are such. 

 The top or crown is stem, and stands at the sur- 

 face of the ground ; and from 

 this portion only are young 

 plants or flower -stalks produced. 

 It is strange that while both 

 root -tubers and stem -tubers usu- 

 ally produce sprouts or young 

 plants throughout their length, 

 these crown -tubers do not pro- 

 duce sprouts from the root 

 portion. 



458. Tubers 

 "' directly serve 

 the purpose of 

 propagation, but 

 may merely 



carry the plant 

 over an unpro- 

 season, 

 it to 

 continue its growth and to resume 

 its normal functions upon the ap- 

 proach of congenial conditions. 

 In fact, beets, turnips, radishes, 

 and other simple crown -tubers are 

 of this class. So are great tribes 

 of cacti, in which the plant-body 



Fib. 382. 



Crown-tuber of salsify or pitioUS 

 "vegetable-oyster." 



and allow 



FiQ. 383. 



Root-tuber of multi- 

 florus beau. 



