TRITICUM 



53 



Conj 



Fia. 19. Triticum. A, transverse section of a rhizome or stolon; Ep, epidermis; 

 MS, a vascular bundle situated in the cortical parenchyma; End, endo- 

 dermis. B, continuation of section figures in A showing corticarparenchyma 

 (C) ; endodermis (End) ; sclerenchymatous fibers or stereome (S) surrounding 

 a mestome strand with two large tracheae having porous walls and small 

 tracheae with annular thickenings between them; parenchyma cells of pith 

 (P). C, a vascular bundle or mestome strand from the cortex (07) showing 

 that it is surrounded by a closed sheath of sterome (S) and contains almost 

 exclusively leptome. D, transverse section of a portion of a secondary root; 

 C, thick-walled cells of inner layer of cortex; End, endodermis; P, peri- 

 cambium; PL, the proto-leptome; PR, the proto-hadrome in which the 

 earliest vessels are developed; V, portions of two tracheae; Conj. thick 

 walled conjunctive tissue. After Holm. 



