136 HISTORY OF BRITISH PERNS. 



Marshy places and damp woods are the situations in which 

 this Fern is met with ; and in such places it does not appear 

 to be uncommon. It is very easily cultivated on damp 

 banks or rock-work, and, when grown in pots, requires to be 

 plentifully supplied with water. 



LASTREA THELYPTERIS, Presl. The Marsh Fern. (Plate 

 VI. fig. 1.) 



This is called the Marsh Fern from its growing in marshes 

 and boggy situations. It has a slender, extensively creeping 

 stem, which is usually smooth and of a dark colour, pro- 

 ducing matted fibrous roots. The annual fronds are pro- 

 duced about May, and later, and perish in the autumn : they 

 usually grow about a foot high, the fertile ones taller ; some- 

 times, when the plant is very vigorous, they reach the height 

 of three feet* Their texture is delicate, their colour pale 

 green, their outline lanceolate, their mode of division pin- 

 nate, the pinna3 mostly opposite, a short distance apart, and 

 pinnatifidly divided into numerous crowded, entire, rounded 

 lobes ; the lobes in the fertile fronds appear narrower and 

 more pointed that those of the barren, on account of their 

 margin being revolutely bent under. 



The venation of the lobes of this Fern consists of a 

 distinct, somewhat tortuous midvein, from which alternate 



