72 MINNESOTA WEEDS 



early in August. This pollen is dreaded by hay fever sufferers. The 

 seeds of ragweed are very similar to those of kinghead, except that 

 they are smaller. They are brown in color and have sharp points 

 at the large end of the seed. Ragweed causes dairy men a great deal 

 of trouble because it taints the milk and butter when eaten by cattle. 



The plant flowers in July and early in August, and ripens its 

 seeds in August. It is found along roadsides and waste places in 

 all parts of the State and grows in all kinds of soil, but thrives espe- 

 cially well in rich black loam. The seeds are very commonly mingled 

 with red clover seed and cereals. 



Eradication. — Ragweed is an annual which grows in rich soil 

 that is not fully occupied by a growing crop. A short rotation, 

 three or four years preferably, which includes a grass or clover crop 

 and a cultivated crop, will help to clean infested fields. The culti- 

 vated crop should follow the grass crop and the field must be carefully 

 watched for late plants. Hand hoeing is often required to make the 

 eradication complete. The seed should be prevented from matur- 

 ing if possible. Cutting infested spots and roadside strips before 

 the seed is mature is a common method of holding it in check. 



Burdock {Arctium lappa L.) 



Other common names. — Clot bur, great bur, cockle button, beggar's 

 button, stick button. 



Description. — It is a biennial plant with a large deep tap root. 

 The plant is generally recognized by its large entire leaf which is 

 often more than a foot across. The leaves are generally fuzzy be- 

 neath, and the leaf stalk is hollow. The first year this plant merely 

 develops a leaf and root system. The second year the branched 

 flowering stalk is sent up, sometimes six feet high. At the ends of 

 the branches the purple-tipped flower burs are formed. These burs 

 produce the seed and, when the seed is mature, the burs become 

 yellow brown. The bur is often three-fourths of an inch in diameter. 

 The seeds are gray but spotted with brown. They are about one- 

 twelfth of an inch long and wider at one end than at the other. The 

 burdock is especially bad in sheep and horse pastures as the burs 

 get into the wool of the sheep and the manes and tails of the horses. 



The burdock flowers in July and August, and seeds in September. 

 It is a typical backyard weed but is often found in fence corners, 

 orchards, waste places, and by the roadside. It rarely proves trouble- 

 some in cultivated fields, although it thrives best in rich soil. The 

 seed is seldom found in that of any farm crop, but is distributed by 

 means of the burlike heads with hooked tips which catch and cling 

 to the hair and fur of various animals. 



