54 FERNS 



sections described. Lower down in the 

 border are specimens of the maidenhair. 

 The dark, glossy fronds of the Christ- 

 mas fern (Polystichum acrosticboi3.es) are 

 largely in evidence, contrasting well with 

 the reliable marginal shield fern (Dryopteris 

 marginalis); both in turn foil the more deli- 

 cately cut and coloured spinulose shield 

 fern (D. spinulosa), with its varieties. The 

 most distinguished member of the poly- 

 stichum group is Braun's holly fern (P. 

 Braunn). 



Fine clumps of the purple cliff brake (Pel- 

 Itza atropurpured) are apparently as much at 

 home as they are among the outcropping 

 ledges at the base of scraggy cliffs, whence 

 spores have doubtless been wafted from 

 their inaccessible ancestry above. This fern 

 is interesting and valuable; it is not only 

 beautiful in design but unique in colour, a 

 dark blue-green emphasising all the varying 

 tints about it. It begins to unfold its fronds 

 late in comparison with others, a desirable 

 habit, as the oak fern (Phegopteris Dryopteris) 



