ANGIOSPERM/E 



187 



which the plumule is developed ; the vascular bundles are 

 arranged in a chcle in the stele and usually increase in thick- 



Fig. 937. 1, 2, 3, 4, 5, 6. Successive stages iu tlie development of the ]Moiio- 

 cotj"ledouous embryo of Aluma. h. Hypophysis and the cells derived 

 from it. /. Segment of the hypophysis wliicli gives rise to the root. 

 7. Mature embryo, a. Apex of stem. After Sachs. 



ness by means of a cambium laj^er ; the flower is either 

 tetramerous or pentamerous ; the foliage leaves usually have 

 reticulate venation. 



