XEROPHYTES AND HA l.OPH YTES. 



321 



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

 the excretion of wax or of varii+*ff upon the surface of the epi- 



FTOXrs: 





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, 

 winch 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 



Fig. 36 



Fig. 360. — Prickly pear ( >puntia vulgaris) with Battened jointed stem and no 



leaves. About one fourth natural size, After Frank, 

 Fu;. 361.— Multicellular hairs ol edelweiss, MagnifU d about 50 diam.— After Kerner, 

 Fir.. 362. — Silky unicellular hairs ol Convolvulus Cntorum. Magnified about $" 



ili.1111 Ml. 1 K( ii" 1 



