210 THE BLADDER FERNS. 
bracken. It seems equally 
at home in the Tropics or 
in lands where snow and 
ice abound for nearly 
half the year. 
Of all our native ferns, 
this fragile little species 
is first to put forth its 
fronds in spring. They 
start into growth at the 
first hint of a warmer 
season, being often fully 
spread before those of stouter 
@i,,,_and what appear to be hardier 
species have begun to uncoil. 
Fronds continue to be pro- 
duced all summer when the sea- 
son is favourable, but frequent- 
ly all traces of the plant disappear before 
August if exposed to drought. It is not 
unusual, however, to find fresh and green 
fronds even to November in the latitude of 
southern New York, and the plants that 
wither in summer may revive and put forth 
new fronds later in the year. 
The rootstock is rather slender and creeps 
about in the chinks between the rocks. The 
fronds are seldom more than fifteen inches 
long, the stipe making up a little more than 
half of this length. Mature fronds, however, 
may reach a length of two feet, while moun- 
tain forms may be reduced to four or five 
inches. The blade is thin, narrowly oblong- 
COMMON BLADDER FERN. 
Cystoplteris fragilis. 
