324 



PLAN T LIFE. 



moss. 3. Other plants adapt aerial roots to the absorption of 

 moisture from the air, as well as falling water. (See ^ 196.) 

 4. Many are surrounded by the bases of dead leaves, which 

 act as a sponge for absorbing water, and supply it gradually 

 to the stem or younger leaves. Living leaves, sometimes 

 singly, sometimes in clusters, form cuplike or tubular struc- 





FIG. 368. Portion of a vertical section of leaf of oleander. c/>, epidermis of upper 

 face ; e/>', same of lower face with stomata, .y, in deep pits with numerous hairs, / 

 //, palisade parenchyma in two layers; j/, spongy parenchyma; /i, //', hypoderma 

 adapted to water storage. Chloroplasts shown only in left-hand side of figure. 

 Magnified about 175 diam. After Van Tieghem. 



tures, acting as water receptacles, from which it can be 

 absorbed as required. Such adaptations occur chiefly in 

 epiphytes. (See ^454.) 5. Many xerophytes develop ex- 

 ceedingly long tap roots, which penetrate the soil deeply 

 to a permanent water supply, 



