10 MINNESOTA WEEDS 



A biennial weed is one that lives for two years. The first year 

 it starts from the seed and develops a large tap root below the ground 

 and a rosette of leaves above ground, but does not flower or seed. 

 The large tap root is stored full of food which gives the plant an early 

 start the following spring. From the center of the rosette of leaves 

 a stalk is sent up which bears flowers and, later, seeds. At the end of 

 the second year the plant dies. Two good illustrations of this class 

 of weeds are the bull thistle and the burdock. 



A perennial weed is one which can grow year after year without 

 reseeding and is, in most cases, the worst kind of weed to eradicate. 

 A perennial weed is frequently provided with running underground 

 roots, or rootlike stems called root stalks. The root stalks run 

 underground parallel to the surface of the ground and at intervals 

 send up branches which may later on be separated from the main 

 plant and may become independent plants and form flowers and 

 seeds. In some cases, such as the Canada thistle, true roots form 

 underground runners similar in appearance and action to the root 

 stalks. The root stalks of some of the perennial weeds lie near the 

 surface, while in others they are some distance below the surface. 

 The root runners of the Canada thistle and the root stalks of the wild 

 morning glory and the perennial sow thistle are quite deep, while 

 such plants as quack grass and sheep sorrel have their underground 

 stem systems near the surface. Canada thistle has been found to have 

 roots two and one-half feet below the surface of the ground. It can 

 be seen, then, that a perennial weed has two ways of propagating 

 itself: (1) by running underground roots and root stalks, and (2) by 

 seeds in a manner similar to that of the annual weeds. 



LOSSES CAUSED BY WEEDS 



When growing with crop plants, weeds rob the soil of much food 

 and moisture which should be used by the other plants. For this 

 reason the cultivated plants often become weak, owing to insufficient 

 food and moisture. Weeds are usually hardy and prolific. They 

 will thrive especially well in carefully prepared soil if given the chance. 

 Unless they are kept down by proper cultivation and crop rotation 

 they soon overrun the land. 



The cost of eradication of such weeds as quack grass and the 

 Canada thistle is very great. To eradicate quack grass from an acre 

 of badly infested land often costs from fifteen to twenty dollars. 



Weed:, are no1 only unsightly on farm lands but greatly reduce 

 I lie value of the land. Some farms, especially when left in the hands 

 of shiftless renters and owners, become so infested with weeds thai 

 i he value of the land is reduced ten to t went v dollars per acre. Dock- 



