28 FERNS OP GREAT BRITAIN. 



though preserving well the outline of this fern, gives 

 no idea of its attitude while living. This is gently 

 drooping, not only the whole leafy portion bending 

 down, but the lobes curving down also. 



4. P- calcdreum (Limestone Polypody). — Fronds tri- 

 angular, somewhat three-branched, lower branches pin- 

 nate, the pinnse pinnatifid, blunt, the uppermost nearly 

 entire ; fructification marginal. This plant is also known 

 as Smith's Polypody, or Rigid Three-branched Polypody. 

 Notwithstanding, however, its latter name, it is far less 

 distinctly three-branched than the last species, and is 

 very different from it in its habit. The lower branches 

 are much smaller in proportion to the middle one, and 

 aU are erect and rigid. It has not either, in any great 

 degree, the angular bend in the stalk of the frond whi©h 

 so well characterises the Oak Fern, though it in some 

 specimens slightly shares this peculiarity. It is also a 

 more rigid firm plant, of a darker, duller green ; its stalk 

 is more scaly at the lower part, and green instead of 

 purple ; its clusters of fructification usually more densely 

 crowded ; it has also a marked distinction in the mealy 

 appearance presented by the surface, owing to numerous 

 stalked glands which crowd over every part of it. The 

 fronds are from six inches to a foot high, nearly tri- 

 angular, the base shorter than the sides. The stalk is 

 of about the same length as the leafy part ; but the side 

 branches are not only shorter, but are more slender than 

 the middle one. The lower branches are pinnate, and 

 the pinnae are cut down nearly to the midrib ; the upper 

 branch is pinnate, with its lower pinnae again pinnate, 

 and the upper ones pinnatifid, as are also those of the 



