FOLIAGE LEAVES: THE LIGHT-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 (Adiantum) leaflets. 
neath, while the leaf blades have been carried to the upper 
side and have assumed a mosaic arrangement. 
Sprays of maidenhair fern (see Fig. 22) show a remark- 
able amount of adjustment of the leaflets to the light side. 
Another group of fern-plants, known as club-mosses, has 
horizontal stems clothed with numerous very small leaves. 
These leaves may be seen taking advantage of all the space 
on the lighted side (see Fig. 21). 
