CRUCIFERAE (MUSTARD FAMILY) 



179 



Means of control 



Infested grain fields and meadows should be sprayed with Iron 

 sulfate or Copper sulfate before the first flowers mature. Stubbles 

 should be cultivated after harvest in order to destroy autumn 

 seedlings. 



SWINE CRESS 



Cordnopus didymus, Sm. 

 (Senebiera didyma, Pers.) 



Other English names : Lesser Wart Cress, Carpet Cress. 

 Introduced. Annual or biennial. Propagates by seeds. 

 Time of bloom: March to June. 

 Seed-time: Early May to August. 



Range: Newfoundland to Florida and Texas, westward to Cali- 

 fornia. 

 Habitat: Yards, roadsides, waste places. 



Grazing cattle usually avoid plants with a disagreeable odor, but 

 they seem to make an exception of the Mustards. The smell of 

 this weed is suggestive of a pigsty, 

 whence its name of Swine Cress ; it 

 is occasionally the cause of damaged 

 dairy products. (Fig. 123.) 



Stems four inches to a foot in 

 length, prostrate, diffusely branched, 

 hairy, spreading on all sides from 

 the root. Leaves very deeply pin- 

 natifid, some but once, others with 

 the segments also cut ; upper ones 

 sessile but those near the base having 

 slender petioles. Flowers white, ex- 

 tremely small, in slender axillary 

 racemes on short, threadlike pedicels. 

 Autumn plants flower earliest, com- 

 ing into bloom as soon as uncovered 

 from winter snows. Silicles small, 

 valves separating readily into two 

 taining one seed. 



FIG. 123. Swine Cress (Corona- 

 pus didymus). X i- 



wrinkled, warty, the two 

 ovoid nutlets, each con- 



