IOWA ACADEMY OF SCIENCES. 



161 



EXPLANATION OF PLATE. 



Asplenium Tbelypteroides. 

 Asplenium Filix- foemina. 

 Scolopendrium vulgare, 

 Camptosorus rbizopbjllus. 

 Pbegopteris calcarea. 

 Pbegopteris Dryopteris. 

 Pbegopteris Polypodioides. 

 Pbegopteris alpestris. 

 Aspidium spinulosum. 

 Aspidium Oreopteris. 

 Aspidium Noveboracense. 

 Aspidium Tbelypteris. 

 Aspidium acrosticboides. 

 Aspidium unitum. 

 Aspidium Loncbitis. 

 Nepbrolepis exaltata. 

 Cystopteris bulbifera. 

 Onocloa sensibilis. 

 Woodsia obtusa. 

 Woodsia Ilvensis. 

 Woodsia glabella. 

 Dicksonia punctilobula. 

 Tricbomanes Petersii. 

 Lygodium palmatum. 

 Aneimia adiantifolia. 

 Aneimia Mexican a. 

 Osmunda cinnamomea. 

 Osmunda regalis. 

 Scbizeea pusilla. 



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, OnocJea Struthiopteris has relatively small spores. 



Fig. 56. Spores of ferns, 

 Ameimla Mexicana. 



11 



Fig. 58. Osmunda 

 regalis. 



Fig. 59. Schizoli 

 pusilla. 



