114 THE SCHOOL GARDEN BOOK 



only the strongest seeds, surest to produce plants true to the 

 type preferred, still preserve good vitality; so large grovt^ers of 

 cucumbers prefer such seed where the percentage of ger- 

 mination is low. Similarly, seed of double balsam gives a 

 larger percentage of double flowers if aged until the weaker 

 seed has lost power of germination. 



THE CLASSIFICATION OF VEGETABLES 



The crops that are commonly grown as garden vegetables 

 may be classified in various ways. One of the most satis- 

 factory arrangements is that adopted by Professor L. H. 

 Bailey in his book, "The Principles of Vegetable Garden- 

 ing," which is reproduced with slight modifications in the 

 diagram on the following page. According to this system, 

 which is based on methods of culture, garden crops are first 

 arranged into those which are grown as annuals and those 

 which are grown as perennials. Of the latter, the asparagus 

 and rhubarb are much the most important, while the former 

 includes nearly all the crops which we commonly think of as 

 vegetables. 



As will be seen by the diagram, these annuals are arranged 

 under three main groups. The first includes those crops in 

 which the underground part of the plant is utilized, these 

 underground parts consisting sometimes of roots, sometimes 

 of tubers, and sometimes of bulbs. The next group includes 

 those crops in which the leaves and leaf stems are eaten, and 

 the third in which the seeds and fruits are eaten. 



The six most important Root Crops are the beet, carrot, 

 parsnip, radish, salsify, and turnip. In all of these the edible 

 portion for which the crops are grown consists of a thickened 



