and Woody Tissues of Ferns. 325 



Polypodium alpestre. 



The petiole has two flattened fasciculi, without dark sheaths, 

 which, as they pass upwards, run into one of a horseshoe sec- 

 tion, with the convexity towards the back of the stalk. 



The rhizome is of pale tissue, with a brown cuticular layer, 

 and occasionally with a faintly-marked stratum of darker cells 

 surrounding the fasciculi of the netted cylinder*. 



Polystichum Lonchitis. 



The petiole has two large lateral fasciculi, and one or more 

 intermediate, of smaller size, sparingly anastomosing with each 

 other and with the former; all without dark sheaths. 



The rhizome has the fasciculi of the netted cylinder indurated 

 in places by the conversion of part of the cambium-coat into 

 fibres with an internal brown deposit ; but there are no dark 

 tracts in the general parenchyma. 



Polystichum aculeatum. 



The petiole has numerous fasciculi invested with dark sheaths, 

 and sparingly connected by slender transverse branches. 



The rhizome, at the origins of the petioles, has deep indenta- 

 tions running into the interstices of the netted cylinder. The 

 whole substance is of pale tissue, except the cuticular layer. 



Lastrea Filix mas. 



The petioles as in the last species. 



The rhizome is of pale tissue (except a brown cuticular layer), 

 thick and fleshy, with the netted cylinder deeply imbedded in 

 its substance; the vascular fasciculi and their cambium-coat 

 have a brownish tint. 



Lastrea dilatata. 



Petiole and rhizome as in the last species, except that the 

 rhizome has numerous isolated fusiform nodules, of a very dark 

 tissue, in the parenchyma within the netted cylinder. 



Lastrea Oreopteris. 



The petiole has two fasciculi, and a tract of dark tissue on the 

 inner margin of each, meeting its fellow at the point where the 

 fasciculi are connected with the netted cylinder of the rhizome. 



The rhizome is of pale substance, with a cuticular layer of 

 brown tissue ; and a transverse section shows dark spots in the 

 line of the netted cylinder, at the points of convergence of the 

 tracts of the petioles. 



* These characters apply in some degree to all the specimens which 

 have been shown me as of this species, though differing considerably in 

 the general appearance of the fronds. 



