Bbtts. — Eosette Plants at Cass. 275 



The pericycle is a single layer of small thin -walled parenchymatous 

 cells. The phloem and xylem form a continuous cylinder round the pith, 

 which consists of large, rounded cells with somewhat thickened walls. 

 In the xylem the vessels and fibres are polygonal in section and are thick- 

 walled. 



Root (fig. 35). — The diagram is of an old root, in which the piliferous 

 layer has been worn off, exposing the cortex ; the outermost layer is of 



Fig. 35. — Gnaphaliuni Traversii. Transverse section of root 

 ( X 230). a, suberized cortex ; 6, cortex ; c, endo- 

 dermis ; d, phloem ; e, xylem. 



small cells^with the walls, which are thin, slightly suberized. The rest 

 of the cortex consists of oval or irregular cells with thicker walls, and small 

 air-spaces between the cells. 



The endodermis is a single layer of small oval cells with thin suberized 

 walls. The xylem forms a compact central mass, in which the elements 

 are polygonal in transverse section and have thickened walls. The phloem 

 forms a narrow band surrounding the xylem. 



