MAN SPREADS WEEDS 
Then, in his commerce, man has brought seeds of de¬ 
sirable crops from many lands. He has sowed wheat, 
clover, and grass that have come from abroad. It is very 
hard to get seed that is pure and clean. Harmful weeds 
are likely to come in with such seed. Thus man broad¬ 
casts his enemies. 
The common daisy of the fields is an example of a 
harmful plant that has overrun America. It was not 
known here until Europeans came. In Europe, where the 
land is carefully cultivated, it does little harm. But in 
America, where there is much idle land, it has spread far 
and wide. There are probably more daisies in America 
today than in all the rest of the world combined. It 
crowds out useful crops and is itself useless. 
161 
