FERN. 



PTERIS AQU1L1NA. 



A. ASEXUAL GENERATION. 



I. External characters. 



1. Rhizome the brown, underground stem with a 



ridge on each side. 



2. Roots ; springing from the rhizome. 



3. The leaves or fronds: arising from the rhizome 



at intervals along the lateral ridges. 



(a) The subdivision of the frond : the leaf- 



stalk or stipe, and the leaf proper or 

 lamina. The lamina is subdivided like 

 a feather (pinnately) into pinnae; each 

 pinna is pinnately subdivided into 

 pinnulae, the pinnulse in some cases into 

 lobes, and these into lobules. 



(b) The sorus: a band of sporangia under the 



edge of some of the pinnules. 



(c) The mdusium ; the membrane covering the 



sorus. 



4. The nodes and internodes of the rhizome. 



5. The growing point at the end of the rhizome. 

 /Sketch, slioioing these parts. 



II. The rhizome. 



1. Cut one end smooth with a razor and sketch the 



cut surface as seen with the naked eye. 

 (a) The outer brownish layer : epidermis and 

 subepidermis (sclerotic parenchyma); the 



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