442 



THE SMALL GRAINS 



flood waters, while sweet clover, pigweed, sunflower, and 

 mustard seed are carried by irrigation waters. Some 



b .jflRbL ^sv^i C 



Salsola pesttfer polygomun convolvulus 



Lithoepermani arvense 



Ambrosia artemisiaefolia 



Helianujus 



Carduus lanoeolatus 



Carduas arvensis 



Sanctons arvensis 



FIG. 141. Seeds of weeds. Enlarged. 



seeds, as the sandbur and buffalo bur, are carried in the 

 hair of animals. Hay, packing materials, and manure 



