i6 



THE WHEAT PLANT 



a 



r 



FIG. 15. Transverse sections of the embryo 

 showing the arrangement and number of 

 the vascular bundles at different levels. 

 s, Central bundle of scutellum ; a, smaller 

 bundles of scutellum ; i-n, bundles of first 

 foliage leaf ; m, midrib of the same ; B, D, F, 

 bundles of second foliage leaf ; r, lateral roots. 



four belonging to the second 

 foliage leaf disappear before the 

 point of insertion of the first 

 foliage leaf is reached. 



Lower down, near the point of 

 insertion of the coleoptile, the 

 scutellum bundle divides, the 

 right and left halves joining the 

 bundles from the coleoptile just 

 outside the stele. 



Still lower, the bundle 5 from 

 the first foliage leaf coalesces, 

 with bundle B from the second 

 leaf, and similarly bundles 7 and 



FIG. 16. Transverse section of the 

 scutellum and plumule of Abyssinian 

 Emmer (T. dicoccuni). Coleoptile with 

 six vascular bundles. 



F on the other side of the midrib 

 (6) unite with each other : these 

 all join the vascular elements of 

 the pair of lateral rootlets which 

 arise at this point. 



The midrib bundle 6 appears 

 to pass down through the node 

 into the primary root without 

 combining with others, although 

 the anatomy at the node is 

 obscure. 



In regard to the homology of 

 the various parts of the embryo 

 many different views have been 

 advanced. The scutellum is 

 usually considered a cotyledon, 

 although Regel, Hofmeister, 



