204 THE BOOK OF USEFUL PLANTS 



are in recent years quite common in the markets of 

 all cities, being grown and shipped in refrigerator 

 cars from California vineyards. The Flame 

 Tokays, Cornichons, Mission, and Muscats are 

 among these well-known and deservedly popular 

 fruits. 



Some of the finest varieties of cultivated grapes 

 have been developed from crosses of native 

 American species with the European vine. New 

 kinds have been thus produced outright. The 

 game of making hybrids is played by carrying the 

 pollen of one species to the pistils of another, and 

 preventing self-pollenation. Then we plant the 

 seed set as a result of this hand-work at crossing. 

 It succeeds best with species that do not grow 

 alongside of each other, naturally. The wine 

 grape and the American fox grape have produced 

 some of the most successful of these artificial 

 crosses; and the crossing of a hybrid with a na- 

 tive has produced still better varieties. Some of 

 the good varieties are believed to be natural hy- 

 brids, crosses produced by the agency of insects 

 or the wind, instead of the voluntary effort of 

 experimenting horticulturists. 



The grape phylloxera is a plant louse that feeds 

 upon the roots of the vines, causing the plant to 

 die. It was the cause of death to the European 



