IOWA ACADEMY OP SCIENCES. 
161 
EXPLANATION OP PLATE. 
No. 
1. Acrosticbum aureum. 
2. Polypodium vulgare. 
3. Polypodium falcatum. 
4. Polypodium Californicum. 
5. Polypodium pectinatum. 
6. Polypodium aureum. 
7. Gymnogramme triangularis. 
8. Notholsena ferruginea. 
9. Notholsena nivea. 
10. Vittaria lineata 
11. Adiantum capillus- Veneris. 
12. Pteris longifolia. 
13. Pteris cretica. 
14. Pteris longifolia. 
15. Cheilantbes mierophylla. 
16. Cheilantbes Alabamensis. 
17. Cheilantbes riscida. 
18. Cheilantbes lanuguinosa. 
19. Cryptogramme aerostichoides. 
20. Pellaea gracilis. 
21. Pellaea atropurpurea. 
22. Pellaea andromedsefolia. 
23. Pellaea ternifolia. 
24. Ceratopteris tbalictroides. 
25. Lo maria spicant. 
26. Blecbnum serrulatum. 
27. Woodwardia radicans. 
28. Asolenium pinnatibdum. 
29. Asplenium trichomanes. 
30. Asplenium brmum. 
No. 
31. Asplenium Thelypteroides. 
32. Asplenium Filix-foemina. 
33. Scolopendrium vulgare. 
34. Camptosorus rbizopbyllus. 
35. Pbegopteris calcarea. 
36. Pbegopteris Dryopteris. 
37. Pbegopteris Polypodioides. 
38. Pbegopteris alpestris. 
39. Aspidium spinulosum. 
40. Aspidium Oreopteris. 
41. Aspidium Noveboracense 
42. Aspidium Thelypteris. 
43. Aspidium aerostichoides. 
44. Aspidium unitum. 
45. Aspidium Loncbitis. 
46. Nepbrolepis exaltata. 
47. Cystopteris bulbifera. 
48. Onocloa sensibilis. 
49. Woodsia obtusa. 
50. Woodsia Ilvensis. 
51. Woodsia glabella. 
52. Dicksonia punctilobula. 
53. Trichomanes Petersii. 
54. Lygodium palmatum. 
55. Aneimia adiantifolia. 
56. Aneimia Mexicana. 
57. Osmunda cinnamomea. 
58. Osmunda regalis. 
59. Scbizsea 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, Onoclea Struthiopteris has relatively small spores. 
Fig. 56. Spores of ferns, Fig. 58. Osmunda 
Ameimla Mexican a. regalis. 
Fig. 59. Schizol i 
pusilla. 
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