518 



WEED FLORA OF IOWA 



Fig. 395. Chess (Bromns secalinus). Outer epidermis of flowering glume in 



surface view. X 160. 

 (After Winton, Conn. Agr. Exp. Sta.) 



Palet. — The flowering glume and palet of chess are very similar 

 in structure, but the outer epidermis of the latter is barbed on the 

 keel, the stiff hairs often reaching 45m in length. 



Pericarp (F). — The pericarp consists of two layers with rudi- 

 ments of. another layer in parts. 1. The Epidermal Cells (ep) are 

 large, elongated-polygonal, and have thin, non-porous walls. 

 2. Mesocarp. As a rule, the cross-cells immediately underlie the 



St— 



Fig. 396. Chess. Transverse section of fruit. F, pericarp consisting of 

 epidermis ep, and cross-cells q ; S, testa ; N, perisperm ; E, endosperm con- 

 sisting of aleurone layer al, and starch-parenchyma st. X 160. 

 (After Winton, Conn. Agr. Exp. Sta.) 



epidermis, but occasionally traces of the mesocarp are evident. 

 3. Cross-Cells (q). Whether this layer corresponds with the cross- 

 cells of the tube-cells of other grasses, I have been unable to decide. 



