HOW PLANTS ARE INFLUENCED 333 



respect Pines, Spruces, Holly, etc. The branches are 

 protected against evaporation by cork and bark ; the 

 buds, by gums, varnishes, wax, hairs, etc. (see page 

 214). 



(2) Reduced surface obtained by having smaller 

 leaves (Moor plants, Heaths, etc). 



(3) Reduced air content obtained by diminishing 



184. Steins of Callitriche in cross-section: (a) land form, (6) water form. 

 Showing the larger air spaces in the latter. 



the size of the interior air-spaces (Callitriche, Fig. 

 184). 



(4) Reduced evaporation obtained by means of 

 thickened epidermis, as seen in Cacti, Century Plant, 

 Holly (Fig. 185), Oleander (Fig. 192), and most 

 plants of dry situations. 



(5) Reduced evaporation obtained by means of 

 coverings of wax (Sugar-cane, Fig. 186, Eucalyptus, 

 Iris, Spruce), or hairs (Dusty Miller, Wormwood or 



