io8 THE STRUCTURE OF ECONOMIC PLANTS 



segments of the perianth and the inner cycle of stamens by branch- 

 ing in a similar manner. Each carpel has a single vascular bundle 

 which arises as a branch from the trace that supplies the outer 

 perianth segment and outer stamen. The point of divergence of 

 the carpellary bundles is slightly above the level at which the outer 



■•■'^i;*«,i«#Si^<-' 



Fig. 98. A, top view of young flower in which outer perianth lobes almost cover stamens. 

 At about this time, the carpels are differentiated ; B, side view of flower slightly younger 

 than A; C, early differentiation of the three carpels; D, carpels have grown upward until 

 they nearly meet at center ; E, carpels with the style just beginning to form ; F, inturned 

 edges of single carpel showing origin of two ovules ; G, a slightly older carpel than F. (After 

 Jones and Emsweller, Htlgardia.^ 



cycle of bundles of the pedicel branch to supply the outer perianth 

 segments and the outer stamens respectively. (Fig. 99, C.) As a 

 result of this method of branching, each perianth segment, stamen, 

 and carpel is supplied by one main vascular bundle. (Fig. 99, 



F, GO 



Development of the Megagametophyte. — Megasporogenesis 

 and the development of the megagametophyte have been inves- 

 tigated for several species of Allium, including A. Cepa, by Weber 



