506 WEED FLORA OF IOWA 



Broomcorn Millet (Panicum miliaceiim L.). 



The walls of the ovary are similar to those of Digitaria humifusa 

 except that they are wider. The testa is much compressed and 

 consists of several layers of small cells. The cells of the aleurone 

 layer are small, somewhat longer than broad. The cells of the 

 starch layer are similar to those of D. humifusa. 



Barnyard Grass (Echinochloa crusgalli (L.) Beauv.). 



The adherent glumes in this species consist of several rows of 

 parenchyma cells, the inner portion, of one row of thick-walled 

 sclerotic cells with pore canals. The cells of the pericarp and testa 

 are much as in the other species, thin-walled and compressed. The 

 protective features are preserved in the coriaceous glumes. The 

 starch and aleurone layers are similar to those of Digitaria 

 humifusa. 



Hungarian Grass or Millet (Setaria italica (L.) Beauv.). 



The colorless smooth pericarp is but slightly thickened and con- 

 sists of three or four rows of elongated cells. These in colored 

 seeds contain the pigment. The testa is but slightly developed. 

 The cells of the aleurone layer are not much longer than broad, 

 and are densely filled with protein grains. 



Green Foxtail (Setaria viridis (L.) Beauv.). 



Dr. A. L. Winton describes the microscopic structure as follows: 

 Empty Glumes and Glume of Sterile Flower. The lower empty 

 glume is three-nerved and less than 1 mm. long; the upper empty 

 glume and the glume of the staminate flower are five-nerved and 

 2 mm. long. In microscopic structure the tluee are practically 

 identical. 1. Outer Epidermis. Characteristic of this layer are 

 the elongated cells with sinuous side walls and longitudinal rows 

 of pits so arranged that one pit occurs in each concave bend of 

 the wall. On the middle portion of the mature glume each of 

 these pits is so large that it fills completely the bend of the wall, 

 and in addition has a thickened border, half of which coincides with 

 the cell wall, thus giving the tissue a lacelike appearance. This 

 structure is optically delusive, the pit borders often appearing to 

 be the cell walls, but is resolved by careful focusing and comparison 

 with the tissue in earlier stages of growth. In addition to these 



