146 TALKS AFIELD. 



familiar. These stout rhizomes do not often 

 serve as extensive natural propagators, al- 

 though most of them die away at one end 

 and grow at a corresponding rate at the 

 other end. At the newly formed extremity 

 they send up a new stalk, an operation 

 which is repeated every year, while the older 

 stalks die, thus forcing the whole plant 

 slowly along. Any of these underground 

 stems are capable of emitting roots. There 

 are many roots which are very similar to 

 these rhizomes and to subterranean stem- 

 tubers. The sweet potato is a true root, and 

 while it does not possess buds, it has the 

 power of forming them when necessary. It 

 is worth remembering that in eating Irish 

 potatoes we eat a thickened stem, but in eat- 

 ing sweet potatoes we eat a thickened root ; 

 and that when we plant pieces of the tubers 

 of Irish potatoes we are planting buds, but 

 when we plant similar pieces of sweet pota- 

 toes we are planting smooth sections of a 

 root which will soon give rise to buds. The 

 tubers of dahlias are true roots ; so also are 

 beets, carrots, parsnips, radishes, and tur- 

 nips, but in these cases a portion of the stem 

 is also thickened, so that the top of the beet 

 or the turnip is true stem. All thickened 



