THE WOOD FERNS. 143 



ing the regular- 

 ity of the rows. 

 The indusia are 

 minutely glandu- 

 1 a r. According 

 to some authors 

 a third set of 

 fronds intermedi- 

 ate in size be- 

 tween fertile and 

 sterile and which 



Aspidium Boottii. Lowest pinna. 



may or may not 



bear sporangia is produced in late summer. This state- 

 ment would seem to need confirmation. The fronds 

 show their kinship to cristatum by the fact that the fer- 

 tile wither in autumn, while the sterile remain green 

 through the winter. 



This species is found from Nova Scotia to Virginia 

 and Minnesota and is also reported from Alaska. It is 

 most abundant in wet shady places and is especially fond 

 of swampy alder thickets. It appears to be fairly com- 

 mon, although in comparison with other wood ferns, it 

 is rare in collections. 



The Spinulose Shield Fern. 



Thespinulo$e shield fern (Aspidium spinulo sum) .and its 

 varieties are among our commonest species, but their 

 abundance in no wise detracts from their beauty. They 

 are most plentiful in deep nioist woods where they flour- 

 ish in the shelter of rocks and large trees or arch along 

 the mossy banks of streams. 



The species may be distinguished from its relatives 

 and from nearly all our other ferns by its finely divided ' 



