XEROPHYTES AND HALOPHYTES. 



321 



ment of two or more layers of epidermal cells (fi^. 370) ; or 

 the excretion of wax or of varnish upon the surface of the epi- 



FIG. 359. Transverse section of a leaf of a heath (Tylanthus ericoides), showing 

 revolute form. The stomata are on the under (concave) surface among the hairs, 

 which still further impede the transpiration. Magnified 130 diam. After Kerner. 



dermis. The latter often becomes very thick, giving to the 

 leaves a shiny appearance. Wax is usually in the form of a 



FiTTT 



FIG. 361. 



FIG. 360. 



KK;. 362. 



FIG. 360. Prickly pear (;~>/>untia Tulwar is) with flattened jointed stem and no 



leaves. About one fourth natural size. After Frank. 



FIG. 361. Multicellular hairs of edelweiss. Magnitn d about 50 diam. After Kerner. 

 FIG. 362. Silky unicellular hairs <>t ( nn7'<:/7> H/I/S Cut-ormii. Magnified about 50 



diam. After Kerner. 



