526 



WEED FLORA OF IOWA 



Sorrel or Sour Clover (Rumex acetosa L.). 



This species has very small palisade cells, rectangular in shape 

 and with a small cell cavity which occupies only a small portion 

 of the lower end of the palisade cell. No canals or irregularities 

 of cell cavity. The cell is light in color while canal is darker. 

 The sub-palisade portion is composed of small round cells of a 

 variable number. The endosperm is composed of irregularly ar- 

 ranged cells. Measurements: whole seed coats, 38.3/"; palisade 

 cells, 23/*; sub-palisade, 13.2/*. 



Fig. 404. Microscopic structure of the seed of some Polygonaceous weeds. 

 I. Buckwheat {Fagopyrum esculentum). II. Curled Dock {Rumex crispus). 

 III. (Wild Buckwheat or Bindweed {Polygonum convolvulus). IV. Smart- 

 weed {Polygonum persicaria). V. Sorrel {Rumex acetosa). VI. Knotweed 

 {Polygonum erectum). VII. Smartweed {Polygonum Kydropiper). 

 e=epidermis. sd=sclerotic layer. t=testa. al=aleurone layer. p=parenchyma 



cells. 

 (Drawings by L. H. Pammel.) 



