14 



THE AMERICAN BOTANIST 



Mountain Spleenwort. It roots in crannies so narrow that it can 

 only be dug out with difficuhy. 



Among the most interesting of the rock ferns are the 

 Aspleniums. The novice regards them with favor because 

 each form is so clear-cut that he seldom has difficulty in identi- 

 fying it, while the older student knows from long experience 

 that finding some forms is so largely a matter of chance that 

 the possibility of seeing them in a new situation adds zest 

 to many a botanical outing. The Asplciiiuins as a group are 

 not confined to any particular kind of rock, though different 

 species may have individual peculiarities in this direction, and 

 are seldom found far from their preferred habitats. Most of 

 them prefer limestone or other rocks in which lime is present. 

 The maidenhair spleenwort (Aspleniiim trichomanes) appears 

 to be the least particular of the family as regards the kind of 

 rock it inhabits and in consequence is found nearly throughout 

 the world where rocks abound. It is likely to be the first mem- 

 ber of the group to^ be found by the young collector and often 

 is the only one for a long time. Other members of the family 

 are more particular, not only as regards the rocky support, but 



