THE ORGANIZATION OF THE PLANT 



73 



that give color to the leaf. The cells in the layer nearest the 

 upper epidermis are closely joined together and are more or 



FIG. 58. Epidermal cells and stoinata from the leaf of the amaryllis, a 

 monocotyledon. (Much enlarged) 



less elongated at right angles to the surface of the leaf, form- 

 ing the palisade tissue. Below this layer the cells are more 

 loosely joined to form the sponyy parenchyma. The openings 



int 

 ----sto 



FIG. 59. Section through 

 the leaf of the beech 



ep, epidermis; pal, palisade 

 tissue ; sp, spongy paren- 

 chyma ; int, intercellular 

 spaces ; slo, stoinata 



FIG. 60. Section through the leaf 

 of the rubber plant 



cw, cuticle; ep, epidermis; w, water- 

 storage tissue ; pal, palisade tissue ; up, 

 spongy parenchyma; int, intercellular 

 spaces ; sto, stoinata 



between these cells are known as intercellular spaces. The 

 epidermal cells are nearly air and water proof, and to facilitate 

 the exchange of gases and water between the interior of the 



