90 REPRESENTATIVE PLANTS 



4. Try to determine by reference to Successful .Weeds 

 what features are found in the more abundant weeds. Seek 

 in this way to find out some, at least, of the reasons for their 

 success, recording your conclusions on the page opposite 

 your map. 



Reading. Read in the Government Bulletins how weeds 

 damage the crops, and note what is said of the loss caused 

 by them. (Government Bulletins are to be had free for the 

 asking.) 



SECTION HI. A STUDY OF FALL FRUITS 



Statement. Various burs, preferably the burdock and 

 cocklebur; downy fruits as the thistle and dandelion; 

 winged fruit as the ash, hop tree, or maple ; capsules, as the 

 evening primrose, Jimson weed, or others are easily obtain- 

 able for purpose of studying fruit and seed dispersal. 



The burs. 1. Examine carefully the bur with the naked 

 eye and lens. Observe the general shape and numl)er, size 

 and particular form of the structures that make the fruit 

 a bur. 



2. Compare the burs furnished by experimenting on your 

 clothing and find the form that clings most closely. Dis- 

 cover the reason, if possible, in the nature of the bur 

 covering, 



3. Count the seeds in each bur studied. Observe, if pos- 

 sible, plants of the same kind growing in vacant lots. 

 Count the number of fruit heads in a good-sized plant, and 

 from these facts estimate the total seed production. (See 

 lesson on Weeds.) 



4. Bur plants are very often " weeds." From your obser- 

 vations and what you have previously learned about weeds, 

 how do bur plants fill the requirements of a " good weed " ? 



5. Record, from observation or reading, various agents 

 that carry burs from place to place. What advantage to 

 the plant is this dispersal of the bur? 



