VII.] THE BRACKEN FERN. 61 



LABORATORY WORK. 



A. THE FERN-PLANT ; ASEXUAL GENERATION. 



a. External characters. 



a. The brown underground stem or rhizome: its 

 nodes and internodes. 



b. The roots springing from the rhizome. 



c. The leaves or fronds arising from the rhizome at 

 intervals. 



a. The great amount of subdivision of the frond : 

 its main axis (rachis) ; the primary divisions or 

 pinnce ; the ultimate divisions or pinnules. 



ft. The sori; small brown patches along the mar- 

 gin of the under surface of some of the pin- 

 nules. 



d. The nodes and internodes of the rhizome. The 

 absence of a terminal bud on it. 



b. The rhizome. 



1. Cut it across and draw the section as seen with the 

 naked eye. 



a. The outer brownish layer (epidermis and suit- 

 epidermis.) 



b. The yellowish- white substance (parenchyma) form- 

 ing most of the thickness of the section. 



c. The internal incomplete brown ring (sderenchyma) 

 imbedded in the parenchyma. 



d. The small patches of sclerenchyma scattered 

 about in the parenchyma outside the main 

 sclerenchymatous ring. 



