LABORATORY MANUAL IN FIELD CROPS 37 



PRACTICUM NO. 28 



Object. A Study of Some of the More Common Weeds. 



Materials. Dried samples of weeds. It is better, when 

 possible, to do the work in the field. 



Method. Examine each of the following weeds and answer 

 the questions as given below : chess or cheat grass, dandelion, 

 sweet clover, sour dock, Australian salt bush, mustard, John- 

 son grass, crab grass. Others may be added when deemed 

 advisable. 



STUDIES 



1 . Is it an herb or a shrub ? 



2. Is it an annual, biennial, or perennial ? 



3. Root : fibrous, tap, rhizoidous, fleshy, stout. 



4. How deeply do the roots penetrate ? 



5. Is it a drooping or an erect plant ? 



6. To what group of plants is it closely related ? 



7. Why has this plant become a weed ? 



8. Is it bitter, or tough? Would stock eat it? 



9. In what particular is it different from its relatives ? 



10. Leaves : broad, drooping, narrow, erect, glabrous, hairy. 



1 1 . Do its seeds have arrangements for transportation ? 



12. Would you judge it to be easily krlled by plowing? 



13. Would you judge it to be easily killed by spraying? 



14. Discuss and give methods for eradication. 



REFERENCES 



Bailey's Cyclopedia of American Agriculture, Vol. 2. 



Hunt's Cereals in America. 



Ohio Bulletin No. 175. 



Livingston's Field Crop Production, p. 219. 



