ALLIUM CEPA 



103 



meristematic growing point from which the flowers arise; so that, 

 during early ontogeny, the flower cluster is protected by the invo- 

 lucre as well as by a series of bracts which lie within. Each bract 

 surrounds the primordia of several individual flowers. 



c par 



mx 



Fig. 95. A sector of a transection of flower stalk near base : c par, chlorophyll parenchyma; 

 ep, epidermis ; g c, guard cell ; mx, metaxylem ; par, parenchyma ; ph, phloem ; pi, pith ; 

 px, protoxylem; xj, xylem. 



In the mature flower stalk, the epidermis is protected by a thick 

 lamellated cuticle; and the cells are radially elongated with thin 

 radial walls and somewhat thickened inner tangential ones. The 

 sunken stomata are numerous and open into substomatal cavities 

 in the palisade tissue. (Fig. 95.) The chlorophyllose region 

 consists of one or more rows of palisade cells and a row or two of 

 underlying spongy parenchyma in which lactiferous cells, such as 

 are found in the leaf, are located. The parenchymatous cells 

 centrad to the chlorenchyma are large and surround the outer cycle 



