THE INFLORESCENCE 



107 



The rachilla is delicate and flattened with an arrangement of tissues 

 similar to that found in the rachis. The epidermal cells have straight 

 walls not greatly thickened. 



Numerous hairs are usually present. 



There are generally three slender vascular bundles running through 

 the thin-walled ground tissue. 



The structure of the empty and flowering glumes resembles that of 

 the ordinary leaf-sheath. 



The outer epidermis of the empty glume consists of rows of oblong 

 cells 80-100 p, long and about 25 /x broad, with oval kidney - shaped 

 " dwarf" cells 16x25^ between them at short intervals. The walls of 

 these cells have characteristic wavy thickenings and 

 simple pits (Fig. 81). The margins of the glumes 

 are fringed with hairs, and trichomes of variable 

 length are present on the outer surface, some being 

 only short thick- walled papillae about 16 /x high. 



FIG. 81. a, Epidermis of empty glume ; b, of palea ( x 210). 



Hairs are also found sometimes on the inner epidermis of the glume. 



Rows of stomata occur especially in the apical region of the glume. 



The cells of the inner epidermis have thinner walls ; a few stomata are 

 seen, and numerous hairs 50-70 //, long are also found on the inner surface, 

 especially in the parts over the midrib and stronger nerves of the glume. 



Narrow longitudinal green bands of thin-walled parenchymatous 

 tissue accompany the vascular strands ; the rest of the ground tissue has 

 thickened walls. Delicate vascular bundles traverse the glume longi- 

 tudinally and anastomose near the apex, the midrib strand terminating 

 in the apical tooth. 



The tissues of the flowering glume are similar in many respects to those 

 of the empty glume ; stomata and hairs occur on both surfaces. 



