4 HORTICULTURE FOR SCHOOLS 



are more than one thousand varieties. Of the grape there 

 are twice as many. Of peaches, more than two thousand 

 varieties have been listed in the state of New York alone. 

 There are many thousands of varieties of fruits and vege- 

 tables. The thoughtful student will at once wonder at this 

 multiplicity of varieties. Whence have they all come? What 

 purpose do they serve? Of what concern are they to the 

 student of horticulture? 



3. Varieties not permanent. An historical study likewise 

 reveals some interesting facts. Of the varieties of apples 

 known two hundred years ago, only a few are found in the 

 orchards of today. A variety has its period of popularity, 

 being in time replaced by new sorts which fill new needs 

 and thrive better under new conditions. Sometimes a 

 form like the Newtown Pippin apple or the Concord grape 

 remains for many years a standard, but these outstanding 

 exceptions tend only to emphasize the general rule, that 

 new varieties are constantly appearing and old ones are 

 passing. 



4. Change is universal. This phenomenon of change is 

 not limited to varieties of fruits. John Muir, in Our National 

 Parks, expresses this universal law of life. "Nature is ever 

 at work building and pulling down, creating and destroying, 

 keeping everything whirling and flowing, allowing no rest but 

 in rhythmical motion; chasing everything in endless song 

 out of one beautiful form into another." He was thinking, 

 when he wrote, of forests and meadows, of glaciers and 

 streams, of what we are pleased to call "the everlasting 

 mountains"; but his words are equally true of the cultivated 

 forms of plants. 



5. The nightshade family. The nightshades illustrate the 

 variety in form that plants exhibit and the way in which man 

 has availed himself of this variety in search of food. The 

 common black nightshade grows wild in all parts of the 

 United States. With its small white or violet colored bios- 



