THE AXGIOSPKR.MAK : LI- A\ KS 



lOOI 



their xylem towards the upper surface of the leaf. In Dicotyledons thev are 

 often surrounded by a layer of non-chlorophvllous cells, 'rich in sugars, 

 called the bundle sheath. 



7>^ i 



f 







^ 



v 



Fig. 986. — Pyius mains (Apple). Transverse 

 section of leaf showing a double palisade 

 layer, spongy tissue and an open stoma in 

 the lower epidermis. 



M 



\ l_4-V— Palisade 



upper epidermis 



Vein 



Spongy tissue 



Stoma in lower 

 epidermis 



Fig. 987. — Buxus se^nperrirens (Box). Transverse section 

 of leaf showing the position of the veins in the median 

 plane of the leaf. 



