ANGIOSPEEMjE 



187 



which the plumule is developed ; the vascular bundles are 

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



Fiy. 937. 1, 2, 3, 4, 5, 6. Successive stages iu the development of the Mono- 

 cotyledonous embryo of Aluma. h. Hypophysis and tiie cells derived 

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

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



ness by means of a cambium layer ; the flower is either 

 tetramerous or pentamerous ; the foliage leaves usually have 

 reticulate venation. 



