Description of Ragzveed and Kinghcad. 141 



infested neighborhood, without concen- 

 trated action on the part of the farmers. 



(6) RAGWEED. 



Ragweed (Ambrosia artcmisicefolia) and 

 kinghead {Ambrosia trifida) are annual 

 plants, with slender, much-branched stems. 

 There are several varieties of ragweed, but 

 the varfety represented in the sketch and 

 the one known as kinghead are by far the 

 most troublesome ones. Ragweed more 

 commonly grows to the height of from 

 fifteen to twenty-one inches, though in 

 some soils it will, under favorable conditions, 

 grow to the height of four feet. King- 

 head is usually more vigorous, growing 

 from three to six feet high. The blossoms 

 have a yellow^ish tinge, but the contrast in 

 color between them and the leaves is not 

 marked. The seeds are small and helmet- 

 shaped, and when ripe are of a dark hue. 

 They are produced on the lower portions 

 of the flower-bearing parts of the branches, 

 and are very numerous. They are so light 

 that they float readily in water, and they 

 are possessed of great vitality. 



These weeds usually do not develop 

 until late in the season ; they sometimes do 



