PLANT ORGANS AND ORGANISMS 



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spaces. The lower epidermis is more or less hairy. Examples: 

 Dog's Tooth Violet, Asteis. 



2. Mesophytic. Leaves tend to subdivision, either to slight or 

 moderate lobing, seldom to complete subdivision in pinnate or 

 tripinnate fashion. Example: Dandelion. In microscopic struc- 

 ture, they consist of an upper and lower epidermis, the upper epider- 



FIG. 87. Photomicrograph of cross-section through a portion of the leaf of a 

 xerophyte, Ficus elastica, showing upper epidermis (u.e.), water storage tissue 

 (iv.s.), cystolith suspended on stalk within a cystolith sac (cys), palisade paren- 

 chyma (p.p.), spongy parenchyma (s.p.), vein (v), lower epidermis (I.e.), and 

 stoma (s). (Highly magnified.) 



mis being the thicker of the two. The stomata are wholly or are 

 mainly on the lower epidermis. Hairs are seldom seen. The pali- 

 sade mesophyll is toward the upper surface, the spongy mesophyll 

 toward the lower. The intercellular-air-spaces in the spongy paren- 

 chyma are small. 



3. Xerophytic. Leaves characterized by a thick upper and lower 

 cuticle and by having their numerous, small stomata restricted to 



