194 AGRICULTURE 



apt to have an infested farm. He lets the daisies go to seed in his 

 pasture and they take possession of it. He leaves the thistle in the 

 fence corner, the cocklebur and burdock by the brook, and they 

 sow thousands of seeds. Perhaps he does not practice rotation of 

 crops; certain weeds take advantage of the habits of certain agri- 

 cultural plants, and become established with them. He leaves 

 land out to 'rest/ and a weed crop grows on the grain stubble. 

 A 'resting' field is a weed nursery which raises hosts to occupy 

 that and other fields next year. When the farmer plows under 

 their ripened seeds, he plants a crop as surely as when he plows 

 under wheat or oats. The production of a crop of weeds is as 

 great a tax on soil fertility as an agricultural crop, such as cowpeas, 

 which benefits the farm and the farmer. 



Knowledge Needed. The farmer must understand the nature 

 and habits of his crop plants in order to grow them successfully. 

 He must understand those of weeds if he is to carry on successful 

 war against them. 



Annuals. There are many troublesome annuals. As a rule, 

 they are not so persistent of growth nor so deep of root as longer- 

 lived plants, and thus are easier to destroy. They usually produce 

 seed very freely. Among annual weeds are charlock, chess, corn 

 cockle, dog fennel, pigeon grass, bur grass, cocklebur, horse weed, 

 wild lettuce, ragweed, and Russian thistle. 



Ragweed. The ragweed is one of our few troublesome native 

 annuals. It has many local names, bitterweed, hogweed, little 

 ragweed, rich weed, Roman wormwood; its botanical name is 

 Am bro'si a ar te mi' si ae jo li a. As plants have so many local 

 names, it is a good plan to learn the botanical name, which is the 

 same everywhere. Ragweed is found in almost all states east of 

 the Rocky Mountains. It branches freely and its leaves are much 

 divided. The greenish stamen-bearing and pistil-bearing flowers 



