IOWA ACADEMY OF SCIENCES. 



161 



EXPLANATION OF PLATE. 



Asplenium Thelypteroides. 

 Asplenium Filix-foemina. 

 Scolopendrium rulgare. 

 Camptosorus rbizopbjUus. 

 Pbegopteris calcarea. 

 Pbegopteris Dryopteris. 

 Pbegopteris Pohpodioides. 

 Pbegopteris alpestris. 

 Aspidium spinulosum. 

 Aspidium Oreopteris. 

 Aspidium Norehoracense. 

 Aspidium Tbelypteris. 

 Aspidium acrosticboides. 

 Aspidium unitum. 

 Aspidium Loncbitis. 

 Nepbrolepis exaltata. 

 Cystopteris bulhifera. 

 Onocloa sensihilis. 

 Woodsia obtusa. 

 Woodsia Ilrensis. 

 Woodsia glabella. 

 Dicksonia punctilobula. 

 Tricbomanes Petersii. 

 Lygodium palmatum. 

 Aneimia adiantifolia. 

 Aneimia Mexicana. 

 Osmunda cinnamomea. 

 Osmund a regalis. 

 Scbizaea pa sill a. 



These tables show that there are differences with respect to 

 size and character of species; in some genera species show 

 marked differences in size of spores. Schizaea pusilla, the 

 smallest of our ferns, has the largest spores of any species 

 examined, Onoclea Struthiopteris has relatively small spores. 



?-9 



Fig. 56. Spores of ferns, 

 Ameimla Mexicana. 



11 



Fig. 58. Osmunda 

 regalis. 



Fi" 



59. t"(_'hizoli 

 pusilla. 



