LIFE HISTORY OF THE MALE FERN 59 
1, Eprermis, of epidermal cells whose outer walls are brown. 
Some of these cells have grown out as root hairs which surround 
soil particles and absorb water with mineral salts in solution from 
the soil. 
Fic. 32.—Cross section of a fern root. Photomicrograph, showing the central, 
radial diarch bundle and surrounding tissues. Scalariform tracheids of xylem 
patches (x! and x); phloem patches (p! and p*); pericambium (fe); endodermis 
(en); cortex (co). X 300. 
2. Cortex, of many layers of cortical parenchyma cells with 
brown walls. The outer layers of cells of this region are thin- 
walled, while the extreme inner ones are lignified and form a 
sclerenchymatous ring which surrounds the endodermis. 
3. ENDODERMIS, a single layer of cells tangentially-elongated, 
whose radial walls are lenticularly thickened. 
