PLANT PROBLEMS 69 



Control of weeds. Select the largest specimens to be found 

 in roadsides and vacant lots, barnyards, and gardens, of per- 

 haps ten of the worst local weeds; dry carefully, thresh out 

 and count or estimate the number of seeds in each. No one 

 who takes part in such a lesson can ever be indifferent to al- 

 lowing sucH weeds to ripen their thousands or even millions 

 of seeds, 1 when a stroke of scythe or hoe at the right time 

 would stop them. 



Failure to study weeds and get clear ideas of their powers 

 of reproduction and of effective methods of exterminating 

 them is responsible for the fact that more decisive headway 

 has not been made in their control. Further topics in this 

 connection are the following : 



Dispersal of weed seeds. Along with rats, English sparrows, 

 the San Jose scale, and gypsy moth, many of our worst weeds 

 are immigrants from the Old World. They come mixed with 

 seeds / and grains, in merchandise, and in all kinds of packing 

 materials. Watching ports of entry has not succeeded in keep- 

 ing out these unwelcome guests. Our only hope lies in knowl- 

 edge sufficient to recognize and give the alarm and unite in 

 eradicating vicious importations before they become widely 

 established. 



The more widely a plant is able to scatter its seeds, the 

 better the chance of growth. Naturally weeds lead the world 

 of plants in effective devices for dispersing their seeds. They 

 are aided by different elements in the environment winds, 

 flowing waters, and animals. Make a collection of weed seeds 



1 This suggestion carried out in the Cleveland Normal School yielded the 

 following results : 



Milkweed Asclepias syrlacea 2,510 seeds 



Sticktights Bidens frondosa 7,040 seeds 



Pigweed Amaranthus hybridus 305,760 seeds 



Purslane Portulaca oleracea 1,250,000 seeds 



Lamb's-quarters Chenopodium album .... 1,613,320 seeds 

 Worraseed Chenopodium anthelmir>ticu>n . . 26,085,150 seeds 



