626 



WEED FLORA OF IOWA 



Sorrel or Sour Clover {Bumex 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 {Bwmex crispua). 



III. (Wild Buckwheat or Bindweed (.Polygonum convolvulus). IV. Smarts 



weed (Polygonum persicarta). V. Sorrel (Bym,ex acetosa). VI. Knotweed 



(Polygonum ereotum). VII. Smartweed (Polygonum hydropiper) . 



e=epldermls. sd=sclerotlc layer. t=testa. al=aleurone layer. p=pareiichyma 



cells, 

 (Drawings by L. H. Fammel.) 



