V s 
Fig. 59- — Photomicrograph of cross-section through a portion of the leaf of a 
xerophyte, Ficus elastica, showing upper epidermis ( u.e .), water storage tissue 
( w.s .), cystolith suspended on stalk within a cystolith sac ( cys ), palisade paren- 
chyma ( p.p . ), spongy parenchyma ( s.p .), vein (»), lower epidermis ( l.e .), and 
stoma (s). (Highly magnified.) 
ture, they consist of an upper and lower epidermis, the upper epider- 
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 
PLANT ORGANS AND ORGANISMS 131 
spaces.. The lower epidermis is more or less hairy. Examples: 
Dog’s Tooth Violet, Asters. 
2. Mesophytic. — Leaves tend to subdivision, either to slight or 
moderate lobing, seldom to complete subdivision in pinnate or 
tripinnate fashion. Example: Dandelion. Tn microscopic struc- 
