180 AGRONOMY 



but it is still rare except in the vicinity of railroads. Other 

 weeds owe their appearance in new regions to their having 

 been brought in with the seeds of cultivated crops. The corn 

 cockle (Agrostemma giihago) owes its common name to the 

 fact that it is nearly always found in grainfields, where its 

 seeds have t>een carried with the grain. 



PRACTICAL EXERCISES 



1. Make a list of the weeds known to grow in your locality. 



2. What qualities make them bad weeds ? 



3. Make a list of the weeds that spring up in the school garden. 



4. Underscore the weeds in the above lists that are perennials. 



5. Make a collection of weed seeds labeled with both scientific and 

 common names. 



6. Make a list of the ways in which these weed seeds are distributed, 

 with examples of each. 



7. Estimate the number of seeds produced by one weed in a season. 

 If all these seeds should grow the following year and produce the same 

 number of seeds and continue to reproduce in this way, how many years 

 would it take to produce one plant for each acre of land in the world ? 



8. Make a list of weeds that have come into your region witli the 

 seeds of cultivated crops. Make a similar list for those that have come 

 in along the railroads. 



References 



Long, "Common Weeds of the Farm and Garden." 

 Pammel, " Weeds of the Farm and Garden." 



Farmers' Bulletins 



28. Weeds and how to kill them. 

 188. Weeds used as Medicines. 



Bureau of Plant Industry 



83. The Vitality of Buried Seeds. 

 89. Wild Medicinal Plants of the United States. 

 107. American Boot Drugs. 



