ON LAWN BEAUTIFICATION 



In many sections a weed known as corn cockle 

 (Agrostemma) is a pest in wheat fields. So nearly 

 do the seeds of the corn cockle resemble the 

 kernels of wheat in weight and size that for a long 

 time it was almost impossible to separate the 

 cockle seeds from the wheat. This, of course, 

 caused millers a great deal of trouble for the corn 

 cockle seeds have a black shell about them which 

 discolors the flour. Finally a special machine was 

 constructed for the removal of cockle seeds. 



The perennial morning-glory, commonly called 

 the devil's shoe string, has often palmed seeds off 

 for wheat among screenings fed to poultry, being 

 about the same size and has established itself on 

 much of the best soils in California. 



The darnel (Lolium) commonly called cheat, 

 infests grain fields in some sections and so well 

 have the seeds masqueraded that many farmers 

 thinking their seed was thoroughly clean, later 

 found this weed and have said that the seeds 

 changed into wheat, barley, oats, or whatever the 

 grain happened to be. 



This mimicry, of course, is developed by 

 evolution. That is, those seeds which are most 

 nearly like the seeds with which they are mixed 

 are overlooked in cleaning and remain to per- 

 petuate the race. After many generations of this 

 sort of natural selection, the seeds constantly 



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