APPENDIX. 349 



FERNS. 



Order 1. POLYPODIACE.33. Sporanges on lower sur- 

 face in groups, but never blended. Annulus present, but 

 variable. 



Family I. POLYPODIODIDE^E. Numerous sporanges in 

 sessile sori, divided equally by a vertical annulus. 

 A. No indusium. 



Tribe 1. Polypodiece. Sori at apices of veins. 



* Veins pinnate. 



f Margins of fertile fronds not revolute. 



Gen. 1. Polypodium. Sori globose on apex or back of 

 veins or venules. 



Gen. 2. Marginaria. Sori globose immersed deeply in 

 backs of veins or venules. 



Gen. 8. Pleopeltis. Sori globose on backs of veins or 

 venules, with peltate paraphyses concealing the sporanges. 



t f Margin of fertile fronds revolute. 



Gen. 4. Struthiopteris. Sori globose on backs of veins 

 or venules. 



* * Veins anastomosing. No free veins in the areolse. 

 Gen. 5. Dictyopteris. Sori globose on anastomosing 



venules. Venules anastomosing in irregular hexagonal 

 spots. 



* * * Veins anastomosing. Free veins in areolse. 

 Gen. 6. Niphobolus. Sori globose on apex of venules. 



Venules branched, forming transverse rhomboid spots. 



Tribe 2. Acrostichece. Sporangia scattered over the 

 whole surface. 



Gen. 1. Acrostichum. Sori on all the veins and paren- 

 chyma. Veins branched and anastomosing. 



Gen. 2. Campium. Veins branched, with free venules. 



