I50 Weeds. 



winter annuals, though a few are biennials 

 and perennials. 



The weeds included in this family usually 

 occur in grain fields, gardens, lawns and 

 thin meadows. As they grow rapidly and 

 ripen their seeds with the grain, they are 

 difficult to combat by ordinary means in 

 sections where small grains are grown con- 

 tinuously on the same land for a period of 

 years. Where winter wheat and other 

 winter grains are grown, many of the mus- 

 tard-like weeds grow as winter annuals, 

 developing a rosette of root-leaves in the 

 fall, and starting into bloom and the matur- 

 ing of seeds very early the following spring. 

 As most of the weeds of this family are 

 annuals, they are easily killed by cultiva- 

 tion when small and give little trouble where 

 a good rotation is practiced, with the fre- 

 quent introduction of crops which require 

 frequent cultivation. Naturally, as with 

 other annuals, preventing the plants from 

 seeding is effective, but as the seeds of 

 most of the plants of this family have an 

 oily or mucilaginous covering which effect- 

 ually prevents decay, they maintain their 

 vitality in the soil for many years, and if 



