652 



WEED FLORA OF IOWA 



Fig. 512. Roots of Sour Dock (.Bumeac crispus). 

 (Photographed by Stevens.) 



{Agropyron repens), morning-glory {Convolvulus sepium), smart- 

 weed {Polygonum muhlenbergii), poison ivy {Rhus toxicoden- 

 dron), nettle {TJrtica gracilis), wild rose {Rosa arkansana). 



Fig. 513. Rhizome of Solomon's Seal; a, leaf bud; b, old stem; c, d, old stem 



scars. 

 (After Thom6.) 



