652 



WEED FLORA OF IOWA 



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

 (Photographed by Stevens.) 



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

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

 dron), nettle (Urtica gracilis), wild rose (Rosa arkansana) . 



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



scars. 

 (After Thome.) 



