TRITICUM 



159 



Adventitious Roots. — The roots of the adventitious system 

 arise in the intercalary meristems at the bases of the lower inter- 

 nodes of the culm, and differ from the seminal roots in certain 



-c w 



pbm-dgn 



Fig 68 Median longisection of tip of seminal root : cal, calyptrogen ; co, cortex ; c w, 

 mucilaeinous cell wall; en, endodermis; ef, epidermis; pbm-dgn, periblem-dermatogen ; 

 pel, pericycle; pi, plerome; r c, root cap; stl, stele; ves, cells which become vessel seg- 

 ments. (Redrawn from Percival, The Wheat Plant, Duckworth and Co.) 



