INTRODUCTION 



Howard and Whitten of Missouri planted about 200 species of 

 seeds representing 51 genera to determine whether seeds in general 

 are capable of germinating immediately after ripening if placed in 

 favorable conditions. Seeds of grass, lily, pink, mallow, legume and 

 composite families seem to have no rest period, while rose, cashew 

 and vine families have a pronounced one. In general seeds of woody 

 plants have a more pronounced rest period and are more dif- 

 ficult to force into growth than seeds of vegetable and other her- 





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FIG. 12 TWO STYLES OF PLANT PROTECTORS OR "FORCERS" 



1, closed paper-sided protector with glass top. 2 and 3, forcers in field 

 use. 4, open-sided protector with adjustable glass front which allows of ventila- 

 tion. 



