POLYSTICHUM. 159 



what crescent-shaped, as already explained, often bluntish at 

 the apex, but sometimes acute, always with spinulose mar - 

 ginal serratures, and sometimes, in a few of the lower pin- 

 nules, with deep lobes, so that the pinnules become pimia- 

 tifid. The pinnules are tapered to a broad-angled base, the 

 lines of which usually exceed a right angle, and they are 

 attached to the rachis of the pinna by a short, distinct, 

 slender stalk, which does not form a line with either margin. 



The pinnules have branched free veins ; and the sori are 

 generally ranged in a row on each side the midrib, and are 

 covered by a peltate scale or indusium. 



A form sufficiently distinct to be regarded as a variety is 

 that to which allusion has been made, as having its basal 

 pinnules deeply lobed ; this we call sub-tripinnatum. It 

 does not differ in any other particular, but, being rather more 

 lax than the other forms, is the most elegant of them all. 

 There are many other slight variations, some with narrow 

 acute pinnules, some with blunt rounded pinnules, others 

 with the pinnules deeply serrated, and some very conspicu- 

 ously spinulose, but these differences probably do not point 

 to any permanently distinctive characters. We find the 

 sub-tripinnate form constant in a cultivated state. 



This is a not uncommon Pern, growing in hedge-banks 



