470 



ANNUAL REPORT 



glauca) had 19,499 seeds (fruits.) Green Foxtail Grass, 46,041; 

 Hedge Mustard {Sisymbrium officinale), 36,685; Wild Mustard 

 (8inapsis nigra, L), 131,574. Common Plantain, 43,569. 



VITALITY OF THE SEEDS OF WEEDS. 



Seeds may retain their vitality for years, if not exposed to 

 the air, and properly matured. Giradin sprouted beans that 



/ 



Lactuca scariola. a. Single tioret in the pap- 

 pus and ceroela, the Stamens united about the 

 Style and the Stiguias protruding. Aclienium 

 with long beak and pappus b. attached to its 

 end. c. A single thread of the pappus. 



were over a century old. Some experiments made by Haber- 

 landt in 1861, the percentage of wheat which germinated was 

 as follows: Those of 1850 and '51, none germinated; 1854, 8; 

 1855, 4; 1857, 73; 1858, 60; 1859, 84; 1860, 96. 



Oxygen and moisture are the agencies which put a speedy 

 limit to the duration of the germinative power of seeds. 



Some of the rich bottom lands of this region, when in mead- 

 ows for a few years, show no traces of the Great Ragweed, but 

 when again cultivated, there springs up an abundance of this 



