THE COMMON POLYPODY. 61 
surface of the soil When planted unnaturally deep, or in stiff 
retentive soil, it dwindles, and often eventually perishes. The most 
suitable compost is formed of leaf-mould, peat, and sand. Referring 
to its natural choice of situation, . Mr. Newman observes * :—* It 
leaves the forest tree to rejoice in its vigour, but surrounds with a 
verdant crown the pollard willows that fringe the margins of our 
mill-streams, or overshadow our horse-ponds.” Less happily he 
continues—“ It is emphatically a parasite, a parasite moreover on 
the weak, and when it occasionally makes its appearance far away 
from man, and the works of men’s hands, it is sure to be found 
clinging to some giant of the forest that is hastening to rum.” 
This circumstance of its being frequently met with growing on 
pollard trees, does not, however, give the Common Polypody a 
parasitical character in the proper sense of that term ; it merely | 
proves it to be sometimes epiphytal in habit, and as the plant is 
often found, fully as vigorous, growing among porous earth and on 
sandstone, such conditions are probably all merely accidental, the 
essential ones being a constant supply of moisture more or less in 
quantity, perfect drainage, and moderate shade. The plant will 
even exist in health, naturally, with little or none of some of these 
conditions about it, as many an old wall bears evidence. 
The epiphytal habitats of this species indicate a mode of culture 
which is found to be successful. Like epiphytal orchids, these 
epiphytal Ferns are found to grow well suspended in open shallow 
baskets, the roots being protected by means of sphagnum moss, 
very light peat earth, and silver sand. The baskets should be of 
hazel or ash rods, or of copper wire, and with wide interstices ; 
their form should be broad and shallow, resembling a saucer. ‚In 
planting, a layer of the moss should be laid at bottom, and on this 
some of the rhizomes adjusted so that their points and the young 
fronds may readily push outwards. On these should come a 
stratum of the soil and moss intermixed, and near the top another 
layer of rhizomes partially covered with sphagnum moss. The 
moss is to be packed firm and kept so, by fixing a few cross bars 
at top. The whole should then be well saturated by dipping it in 
soft water, and this may require to be repeated at intervals during 
* Newman, History of British Ferns, 3 ed. 43. 

