AGRICULTURAL BOTANY 169 



Selecting and testing to see which plants are best 

 able to transmit their good qualities have done much 

 to improve our farm crops, the most notable improve- 

 ment being in the sugar beet, corn, barley, tobacco, 

 apple, and potato. The same methods applied to 

 wheat, oats, and grasses will produce like beneficial 

 results. 



One general rule must be followed in all plant breed- 

 ings : Choose the best, then test the yielding and trans- 

 mitting power. 



Note- Experiment stations do systematic work in plant breed- 

 ing, and continue to establish plants of certain desirable characteristics 

 through continuous selection year after year. To facilitate the work 

 of breeding small grains, the plantings are made in plots of ground 

 holding a definite number of plants. These plots are called centgener 

 plots. When the grain is harvested from these plots, it is often desira- 

 ble to inclose each bundle with a cloth cap so that none of the grain 

 may be lost through storms, birds, or insects. These caps may be 

 seen in the foreground of the picture showing a part of the plots of the 

 Minnesota Experiment Station. 



Plant Families. - - There is such a great number of 

 different kinds of plants that to study each kind sepa- 

 rately would take more time than would be possible 

 in the life of any man. Botanists have noted certain 

 general characteristics that are common to certain 

 groups of plants. These common characteristics make 

 it possible to divide the vegetable kingdom into great 

 divisions, classes, orders, families, genera, species, and 

 varieties. By learning the characteristics of a single 

 family or order, he learns certain general things about 

 all the plants that belong to that family. 



All vegetable life consists of four great divisions, - 

 the thallus plants, the moss plants, the fern plants, and 



