170 



WEED FLORA OF IOWA 



Winter Cress (Barbarea vulgaris R. Br.). 



Description. — A biennial, with yellow flowers 1-2 ft. high; stem 

 furrowed, simple or branched; lower leaves simple or pinnately 

 parted, terminal lobe the largest, round or ovate ; upper leaves obo- 

 vate, cut, toothed or pinnatifid at the base ; flowers bright yellow ; 

 pods erect or slightly spreading ; cotyledons accumbent. 



Distribution. — Eastern North America from Labrador to Mary- 

 land, Iowa, Manitoba, Rocky Mountains, Pacific slope; common in 

 northern Iowa. A cosmopolitan weed in Europe, Asia, Africa and 

 Australia. 



Extermination. — This perennial weed is not difficult to kill if the 

 field is given an early plowing followed by a subsequent disking and 

 harrowing, thus getting the field in a good state of tilth for a crop. 



Fig. 95. Winter Cress (.Barbarea vulgaris). 

 (Photographed by Colburn.) 



