204 Trans. Acad. Sci. of St. Louis. 



Panicum glabrum, Gaud. Shows but slight development of 

 the pericarp and testa. The epidermal cells of the former are 

 smaller than the underlying rows of cells of the wall of the 

 ovary. The testa is reduced to a single layer of cells, longer 

 than broad. The aleurone layer is filled with protein grains. 

 The starch cells of the endosperm are large and densely 

 packed with polygonal grains. 



The walls of the ovary of Panicum miliaceum, L. are sim- 

 ilar to those of Panicum glabrum except that they are wider. 



The testa is much compressed and consists of several rows 

 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 the last species (PI. XVIII. 7). 



Panicum Orus-galli, L. The adherent glumes in this species 

 consist of several rows of parenchyma cells. The inner por- 

 tion, of one row of thick- walled sclerotic cells with pore canals. 

 The cells of the pericarp and testa are much as in other spe- 

 cies, thin-walled and compressed. The protective features 

 are preserved in the coriaceous glumes. The starch and 

 aleurone layers similar to those of P. glabrum (PI. XIX. 2). 



Setaria italica, Kunth. The colorless smooth pericarp is 

 but slightly thickened and consists of three to four rows of 

 elongated cells. These in colored seeds contain the pigment. 

 The testa is but slightly developed. 1 



The cells of the aleurone layer are not much longer than 

 broad, densely filled with protein grains. The abutting starch 

 cells are much smaller than the remaining ones. All of the 

 cells are densely filled with polygonal starch grains as in 

 Panicum (PI. XVIII. 5). 



Cenchrus tribuloides, L. The only other member of this 

 tribe studied has a greater development of the pericarp. It 

 is divided into two portions. The cells of outer portion 

 thicker-walled and shorter; the inner of elongated, thick- 

 walled and somewhat fusiform cells. The testa consists of one 

 to two rows of thin-walled cells, much compressed but expand- 

 ing on the addition of chloral hydrate. The aleurone cells 

 are much larger than in Panicum and Seiaria, thick- walled, 



1 Harz. 1. c. 1260. — S. glauca, 1. c. 1259. — 8. verticillata, 1. c. 1260. — 8. 

 viridis, 1. c. 1260. — 8. germanica, 1. c. 1261. 



