CYSTOPTERIS MYRRHIDIFOLIDM. 



97 



WILSON'S FERN, {natural size). 



^nxKdm. 



Genus. — Cystopteeis, (see page 87). 



Species. — MYRRHtDiFOLiUM. Caudex a stolon-like creeping 

 rhizome : stipes erect, longer than the frond : frond deltoid, 

 pinnate : the lowest pair of pinnse nearly opposite, shortly sti- 

 pitate, each almost equal in size to the apical portion of the 

 frond ; all the pinnse once, the lower pair twice pinnate : an 

 obtuse angle is formed at the union of the first pair of pinnae 

 with the stipes and rachis : clusters of capsules circular, and, 

 when the frond is immature, generally accompanied by an ob- 

 scure torn involucre, which is attached to the dorsal surface 

 of the capsuliferous vein immediately behind the point of at- 

 tachment of the capsules. 



