KEY TO THE GENERA. 



309 



Woodward UL 



AapicUum 



Cyatopteris 



Son various ; indusium never formed 

 of the margin of the frond. 



d. Sori and indusium oblong, par- 

 allel with the midrib, somewhat 

 sunken in the tissues of the frond ; 

 indusium opening toward the mid- 

 dle of the pinnules ; water-loving 

 species. Chain ferns. 



WOODWARDIA. 



216 



d. Sori and indusium roundish. 

 t t Indusium peltate, fixed by the 



centre ; evergreen species in rocky 



woods. Shield ferns. 



POLYSTICHUM. Io6 



1 1 Indusium reniform or cordate, 

 fixed by the sinus ; large, mostly 

 woodland species. Wood ferns. 



ASPIDIUM. 117 



1 1 Indusium hood-shaped, attached 

 to the frond by its broad base, 

 below the sorus and arching over 

 it, soon withering ; moisture loving 

 species. Bladder ferns. 



CYSTOPTERIS. 209 



1 1 Indusium star-shaped, of a few 

 irregular broad or narrow seg- 

 ments fixed beneath the sorus and 

 enclosing it when young. Not 

 easily seen in most species. Rock- 

 loving plants usually somewhat 

 chaffy. 



WOODSIA. 93 



