THE FIGHT AGAINST WEEDS 87 



starved out. They rob the plants of moisture as well 

 as of food. In the second place, they serve as a breed- 

 ing ground for insects, as many insects seem to prefer 

 to lay their eggs on weeds. In the third place, they 

 shade small plants and rob them of much needed sun- 

 light. These are the principal reasons why weeds 

 should be destroyed. 



Classification of Weeds. In order to fight weeds 

 to the best advantage we must know something of 

 their life history. They may be divided into three 

 classes annuals, biennials, and perennials. 



Annuals. Plants that go to seed every year and 

 then die, coming up from the seed each year, are called 

 annuals. Pigweed, wild mustard, sweet clover and 

 ragweed belong to this class. It is only necessary to 

 prevent them from going to seed to destroy them. 

 This class of weeds is the easiest one to get rid of. 



Biennials. Plants that live for two years are bi- 

 ennials. They grow up from the seed one year and 

 grow a heavy root, but do not go to seed that year. 

 The next year they come up from the root, go to seed 

 and then die. If we pull them up by the roots the 

 first year, or keep them from going to seed the second 

 year, we can easily destroy them. Cutting them off 

 and not allowing them to go to seed for two years in 

 succession will have the same effect. Mullein, wild 

 parsnip, burdock and bull thistle belong to this class. 



Perennials. Plants that go to seed every year but 

 whose roots live on from year to year are perennials, 

 and the only way to eradicate them is to destroy them 



