CEREAL GRAINS 



FIG. 21. Wheat grain (Triticum sativum): A, transverse section showing epi- 

 carp (e), cells of mesocarp (m), tangentially-elongated cells (querzellen) (t), 

 tube cells (c), spermoderm (s), perisperm (p), aleurone cells (a), parenchyma 

 containing starch (st); B, surface section of pericarp showing relation of 

 epidermal cells (e) to tangentially-elongated cells (t) ; C, hair from the sum- 

 mit of the grain with thick wall and very narrow lumen; D, apical portion 

 of a hair; E, starch grains. 



Rye grain (Secale cereale) : F, hair with wall comparatively thinner than in the 

 hair of the wheat grain; G, apical portion of a hair; H, tangentially-elongated 

 cells in which the pores occur only on the tangential walls; 7, starch grains 

 which vary from 0.020 to 0.070 mm. in diameter, and occasionally have 

 delicate clefts. 



Barley grain (Hordeum sativum): J, transverse section of palet (pa) and peri- 

 carp (pe), aleurone layer (a) composed of two or three rows of cells, paren- 

 chyma of endosperm containing starch (st) ; K, hair from epicarp with very 

 thin wall and large lumen; L, tangentially-elongated cells which differ 

 from those of wheat and rye in being without pores; M, starch grains which 

 resemble those of wheat but are uniformly smaller. 



