WEEDS 



105 



In most of the species of annuals and biennials the only 

 method of reproduction is by seeds which are dormant until 

 the next spring. Winter annuals bear seed in the spring 

 which is dormant until late summer. Perennial weeds may 



Fig. 18. Stages in development of the wild carrot, a biennial plant. The seedling 

 (left), at the end of first growing season (center), a mature blooming specimen in second 

 year (right). (From Maximov's Plant Physiology, after Transeau, McGraw-Hill Book 

 Co., 1938.) 



flower and produce seeds the first summer but usually only 

 after one or more years of growth, when they may produce 

 seeds each year for several years. In many cases, such as 

 dock, the top dies each winter while the root remains alive. 

 Many perennial weeds reproduce most effectively by vegeta- 



