692 WEED FLORA OF IOWA 



fields or flax fields appeared the usual crop of weeds that are car- 

 ried with grain, like com cockle, chess, cow-herb, mustard, penny- 

 cress and darnel. Then came the weeds which were introduced 

 with clover seed as buckhom, dodder, evening catchfly, chicory, 

 wild carrot, etc. 



Fig. 534. Small Peppergrass (.LepiOium, apetalum). Rapidly occupies the vir- 

 gin soil. 

 (Drawing by Charlotte M. King.) 



As our agriculture shifted from a wheat country to one domi- 

 nating in com, the weed flora changed slightly. Corn cockle, chess 

 and vetch {Yicia sativa), so common everywhere in a small grain 

 country, disappeared over a large section of Iowa. They are again 

 appearing where wheat is grown. Charlock, a relic of flax culture, 

 remained to be distributed largely with oats seed. 



