60 



FIG. 25. 



RAGWEED, HOGWEED, BITTERWEED, OR ROMAN WORMWEED. 

 Ambrosia artemisicefolia. 



Ragweed is an annual. The stein is much branched and slightly 

 hairy, from 1 to 3 feet high. The leaves are very finely divided, the lower 

 .surface being of a lighter color than the upper. The flower heads are 

 very numerous, from 1 to 6 inches long, green, and inconspicuous. The 

 -flowers are yellow, 1-6 inch across, infertile in the terminal spikes, and 

 fertile only at the base of the spikes. The seed is dark brown, with 

 & sharp tip, around which are arranged 4 to 6 spines, 3-16 inches long. 

 They have great vitality and remain in the soil a long time without 

 injury. An average plant produces about 5,000 seeds. The seed has a 

 bad taste and gives a peculiar odour to the milk of cows which eat it. 



Time of flowering, July- September. 



Time of seeding, August-November. 



Dispersal as an impurity in seed grain ; and by wind and water, 

 being borne long distances by freshets. 



Eradication. For the eradication of this weed, special attention 

 must be given to the fall cultivation of the soil, to prevent seeds from 

 ripening. Gang-plow or cultivate and harrow stubble ground immedi- 

 ately after harvest, and repeat cultivation at intervals until late in the 

 fall ; then plow or rib up and follow with a hoed crop. Subsequent 

 treatment, the same as for Mustard (Fig. 1 5). 



