racjland] WEED STUDY 160 



the seeds. The seeds were put away for use in the seed analysis 

 work. 



The class had found all the weeds studied to he- very success- 

 ful plants. Next came the study of the characteristics which led to 

 this success. The great number of seeds on each plant had been 

 noticed. In order to get a more definite idea of their power of 

 propagation, three plants of five specimens each were selected, 

 and the number of seeds and space covered by each noted. In 

 estimating the number of seeds, the seeds of a medium-sized 

 branch and the number of branches were counted. In deter- 

 mining the space occupied, the radius of the space shaded at 

 noon was taken as a basis. These problems were worked out 

 with the three plants of each weed and an average of the three 

 then taken. The results were as follows : 



Name. Number of Seed Space Covered 



Willow Lettuce 2435 105 sq. in. 



Indian Mallow 2480 315 sq. in. 



Spanish Needle 1163 78 sq. in. 



Cockle Burr 270 408 sq. in. 



Wild Carrot 880 233 sq. in. 



The number of seeds was large and in order to show the 

 great danger of allowing weeds to go to seed two more problems 

 were worked out. (1) How much space will be required for 

 each weed the second year, in case each seed produces an average 

 plant? (2) How much space will be required the third year? 

 These problems were worked with each of the five specimens 

 with the following results : 



Name Space, Sec. year Space Third Yr. 



Willow Lettuce 6^ sq. rds. 99 a. 



Indian Mallow 20 _ sq. rds. 309 a. 



Spanish Needle 2^ sq. rds. 1G a. 



Cockle Burr &§ sq. rds. 4§ a. 



Wild Carrot 5 sq. rds. 29 a. 



The decision immediately followed that all weed seeds do not 

 produce plants. Some are destroyed by disease, some killed by 

 man or crowded out through his energy, others fall into or are 

 carried to unfavorable places. 



Next, the plants were successful because their seeds could so 

 easily be dispersed. Among the weeds studied, some, such as 

 the white top, Canada thistle, milk weed and dandelion have the 

 papus or feathery hairs attached to the seed, making it easy for 

 the wind to carry them far and wide. Others such as the Spanish 

 needle are gathered by sheep, cattle and man, because of their 



