PLANTS OF IOWA 123 



Filix, Adams. 



1529. F. bulbifera, L. Andrew. Bladder Fern. 

 Moist shaded places. 



1530. F. fragilis, (L.) Undern. Brittle Fern. 

 Rocky woods, frequent. 



Woodsia, R. Br. 



1531. W. ilvensis, (L.) R, Br. Rusty Woodsia. 

 On exposed rocks; rare. 



1532. W. obtusa, (Spreng.) Lorr. Blunt-lobed Woodsia. 

 Rocky places ; infrequent. 



1533. W. scopulina, DC, Eaton. 

 In crevices of rocks. 



Marsilea, L. 



1534. M. vestita, Hook. & Grev. 



In wet sand or in shallow ditches. 

 Mateuccia, Lodaro, 1866. 



1535. M. strutiopteris, (L.) Lodaro. Ostrich Fern. 

 In moist places along streams; frequent. 



Onoclea, L. 



1536. 0. sensibUis, L. Sensitive Fern. 

 In moist meadows and ravines. 



SALVINIACEiE. SALVINIA FAMILY. 



Azolla, Lam. 



1537. A. caroliniana, Willd. Carolina Azolla. 

 Floating on water. 



EQUISETACEA. HORSETAIL FAMILY. 



Equisetum, L. 



1538. E. arvenses, L. Field Horsetail. 

 Common in sandy soil. 



1539. E. pratense, Ehrh. Thicket Horsetail. 

 Frequent. 



1540. E. sylvaticum, L. Wood Horsetail. 

 Frequent. 



1541. E. fluviatile, L. Swamp Horsetail. 

 In wet places. 



