FOLIAGE leaves: THE LICxHT-RELaTION 



27 



leaves (see Figs. 19, 22). In the case of ordinary shade trees 

 every direction of branch may be found, and the resulting 

 adjustment of leaves noted (see Fig. 20). 



Looking up into a tree in full foliage, it will be noticed 

 that the horizontal branches are comparatively bare be- 



FiG. 22. A mosaic of fern (Adianfum) leaflets. 



neath, wliile the leaf blades have been carried to tlie upper 

 side and have assumed a mosaic arrangement. 



Sprays of maidenhair fern (see Fig. 22) show a remark- 

 able amount of adjustment of tlie leaflets to the light side. 

 Another group of fern-plants, known as club-mo'^ses, has 

 horizontal stems clothed with numerous very siuall leaves. 

 Tliese leaves may be seen taking advantage of all tlie space 

 on the lighted side (see Fig. 21). 



