COMMON HARD FEfiN 91 



tion of the barren fronds is dis- 

 tinct, a stout midrib or vein pro- 

 ducing lateral veins once or twice 

 forked, the venules extending pa- 

 rallel toward the margin, and ter- 

 minating in a "small club-shaped 

 head. The venation of the fertile 

 frond, not so distinct on account 

 of the contraction of the parts, 

 differs in having a longitudinal 

 venule on each side the midvein, 

 forming the receptacle to which 

 the spore-cases are attached. The 

 spore-cases are arranged in two 

 linear sori, one on each side of 

 the midvein, distinct while young, 

 but often becoming confluent and 

 covering all the under-surface. 

 The indusia, when mature, burst 

 toward the midrib, and become 

 split, here and there, at points 

 opposite some of the venules. 

 The Hard Fern is an evergreen, 

 not large, but strong and very 

 distinct - looking ; growing in 

 heaths and rough stony places, 

 in woods and shady bottoms, pre- 

 ferring moisture, but careless of 

 situation, and growing in Cum- 

 berland at an elevation of 3,000 

 feet, in Scotland a thousand feet 



