THE STOREHOUSES OF PLANTS 



5 



the leaves, and when it is grafted upon a tomato it has no option 

 but to produce them above ground. 



It is easily seen that many of the storehouses which become 



separated from the old 

 plant, commonly take 

 the place of seeds. 

 The potato tuber is a 

 case in point, and the 

 branches of creeping 

 underground stems will 

 each form a new plant 

 when the old stem dies 

 and rots away. The 

 farmer and gardener 

 know to their cost that 

 any little bit of the 

 stem of twitch grass 

 or of convolvulus can 

 live a separate exist- 

 ence. It would be 

 surprising if we did not 

 make use of bulbs and 

 tubers instead of seeds, in fact, we go even further and induce parts 

 of plants which do not ordinarily part company with their parents 

 to send out roots or shoots, or both. The great point is that the part 

 of a plant which is to lead a separate existence must have, in addition 

 to the necessary powers of growth, sufficient food stored away in it 

 to nourish the new roots and shoots until they can make a living for 

 themselves. It will be found that cuttings need not always be made 

 from stems, though these are by far the most familiar kind. 



Photograph by Wilfred Mark Webb. 



FIGURE 141. A "Geranium 



cutting. 



