RECENT FerRN LITERATURE 29 
study of our native forms is obvious, and the import- 
ance of such monographic work as the present article 
is evident. 
Eleven subgenera are differentiated, noted as probably 
good genera, but conservatively treated under Dryop- 
teris pending further study of Old World forms. 
m. OR: 
Miss E. F. Andrews has given an interesting account 
of the resurrection fern (Polypodium polypodioides). 
This little species is the only fern having a wide range 
in the United States which is habitually an epiphyte. 
Throughout the southeastern states it is a common in- 
habitant of the trunks and branches of trees, often 
occurring, to the astonishment and pleasure of northern 
visitors, on shade trees in city streets. It is not very 
particular as to the species on which it grows. It seems, 
however, never to have been found on any conifer except 
the red cedar and it generally avoids trees with smooth 
or freely exfoliating bark which offer it only an insecure 
foothold. 
Miss Andrews tested the effect of the scales with which 
the lower surface of the fronds is thickly covered, in 
preventing transpiration by removing all of them from 
part of the fronds of a given plant. When exposed sey 
drought, the denuded fronds withered more quickly 
than the others and recovered more slowly when —. 
ure was again supplied. She also tested the fern’s 
capacity for “resurrection” by keeping a mat of it in 
her house wholly without water, and at intervals = 
taching portions of it and supplying them with = 
Six months after the mat had been gathered, a 
fully revived in from 12 to 24 hours after being given 
water; after 14 months and six days of desiccation, one 
root still retained enough vitality to expand two fronds, 
