648 



WEED FLORA OF IOWA 



Fig. 421. Microscopic structures of seeds of some leguminous weeds. 

 I and V. Yellow Sweet Clover (Melilotus officinalis). II- White Sweet 



Clover (Melilotus alba). III. Black Medick (Medicago lupulina). IV. 



Bur Clover (Medicago denticulata) . 

 m=malpighian cells. ll=light line of the same. o=osteosclerid. em=embrya 



t=testa. en=endosperm. p=parenchyma. n=nucellus. 

 (Drawings by L. H. Pammel.) 



