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 

 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. 

 Cystopteris fragilis* 



