SPECIAL FUNCTIONS AND FOBMS OF STEMS 93 



The student should notice that, while budding and grafting 

 are described as modes of vegetative reproduction, their object 

 is not to increase the number of shrubs or trees in the garden or 

 orchard. It is rather a means of propagating the desired kind 

 of plant with certainty for example, to secure a certain 

 variety of fruit. This cannot be done merely by growing seed- 

 ling trees, since every seedling grown from any valuable kind 

 of apple or pear may differ from all the others of the same 

 lot (fig. 163), and not one of them be worth cultivating. 



Grafting often succeeds on plants of different species, 1 as 

 the peach on the plum, the apple on the pear, and the pear on 

 the quince. Sometimes it succeeds between different genera l 

 of the same family, 1 as the tomato on the potato. 



Many technical details best learned from a practical horti- 

 culturist are necessary in order to bud or graft successfully. 



PROBLEMS 



1. What common feature would you be likely to find in the structure 

 of the stems of pickerel weeds, cattails, and rushes, and in the leafstalks 

 of pond lilies and lotuses ? 



2. Large cacti in the deserts of the southwestern United States and 

 Mexico are often cut open in order that their sap may be used for 

 drinking water. Where did the plant get so much water ? How could 

 it have used the water ? 



3. What common garden plants are reproduced by bulbs? Can any 

 of these be grown from seeds ? 



4. Do most kinds of plants grown from bulbs bloom early or late? 

 To what two kinds of climate are such plants suited ? Give examples, 

 among both wild and cultivated plants, to illustrate your answer. 



5. Could more than one kind of scion be top-grafted on a single 

 stock ? Why do top-grafted trees, after they come into bearing, require 

 more careful pruning than ungrafted trees ? What kind of fruit will be 

 borne by shoots that arise below a graft ? 



6. Do bulbs planted in autumn freeze in winter ? What are the best 

 methods and times for the outdoor planting of bulbs in your locality ? 

 Should different plans be used for different kinds of bulbs ? 



1 For the definition of the terms species, genus, and family, see Chapter XIII. 



