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HANDBOOK OF NATURE STUDY 



How to exterminate them. 



As all three are annuals, they are best killed out by pre- 

 venting them from seeding. Cutting or pulling will accom- 

 plish the result. If the plants 

 have already matured seed, they 

 must be burned, after cutting. 



No. 4. The Dog Fennel 

 This weed also is a composite 

 and at once recognized as one. 

 Its flowers have white rays and 

 a yellow disc (the central part) ; 

 the leaves are very finely di- 

 vided. The whole plant has a 

 strong and rather unpleasant 

 scent. It is often a trouble- 

 some weed in meadows and 

 pastures. Early mowing, before 

 the plants have seeds, will ex- 

 terminate it. Why do cattle 

 not keep this weed down ? 

 How are the seeds of this 

 species disseminated ? 



No. 5. The Canada TJiistle. 



This is one of the worst weeds in our Eastern and 

 Northern States, and in Canada. It was introduced into 

 Canada from Europe, and from Canada it has spread into 

 the United States. It is now found from New England 

 to Missouri, and also on the Pacific coast. 



The plant is one to two feet high, has rose-purple flowers, 

 which are smaller than those of the Common, or Bull 

 Thistle ; from which it also differs in its more slender 



FIG. 15. LEAF OF FALSE 

 SUNFLOWER. 



Much reduced. 



Observations. Bats flying about in the evening catching nocturnal 

 insects. 



