HISTOLOGY OF THE FERN 



115 



root and every leaf stalk, the root hairs alone being free from 

 them. The canal system leading into the stalks of the fronds 

 are the most important, forming, as they do, the only means 



FIG. 46. Epidermis from the under side of a leaf, showing the wavy outlines 

 of the epidermal cells, the veins (v) covered by thickened epidermal cells, and 

 guard cells (s.t.) enclosing the stomata. (From Sedgwick and Wilson.) 



of communication between the aerial frond and the underground 

 parts of the fern. 



The Leaf or Frond. The aerial part of Pteridium consists of a 

 main branch or stem arising as an outgrowth from the rhizome. 



