Physiological Anatomy of Xerophytic Selaginellas . 129 
In the first group, the leaves, which stand in a vertical 
direction and are parallel with the stem, form a protection against 
the intense sun’s rays. The growing points of the stems receive 
the rays directly, but the bundle of awns situated on the apex of the 
Fig. XII. Selaginella gatiottei, a hygrophytic species from shady and 
moist greenhouse. Note large and thin-walled cells of hypodermis and 
cortex, and well developed xylem in comparison with S. pilifeva, 1, cross 
section ; 2, longitudinal section. 
leaves reflect the light entirely. All plants have a thick-walled 
epidermis, hypodermis and outer cortex, which are heavily 
impregnated with suberin. The leaves are all surrounded by 
