FERNS 01 GREAT BRITAIN. 87 



by a small line, which is finally hidden by their uniting 

 into one mass. Each of the lines consists of a complete 

 cluster, and when joined together this is called a twin- 

 sorus. This twin-sorus is always placed between two 

 bundles of veins, and covered by the thin white membrane- 

 like indusium of the same form as the clusters. In an 

 early stage, the indusia, touching each other, seem 

 like one only ; then they separate slightly, the distinction 

 between them becoming daily more apparent tUl they 

 finally become widely separated and fall off". This plant 

 was considered of some medicinal use by our fore- 

 fathers, and was included in what were termed the five 

 " capillary herbs." The Golden or Common Polypody, 

 the Common Maidenhair, the Common Spleenwort, the 

 Wall-rue, and Hart's-tongue, formed this group, which 

 was in early days held in great esteem. 



The Hart's-tongue offers a great number of varieties, 

 especially when cultivated, as it so often is, on rock- 

 work. A very elegant and common variety, termed 

 crispum, is so waved and curled at the margin, that it 

 becomes a leafy frUl on each side of the midrib ; it is 

 often of a much paler green than the common form of the 

 Hart's-tongue. Another well-known variety is that 

 termed jpolyschides, in which the frond is narrow, 

 linear, deeply and irregularly cut at the margin into 

 roundish lobes. A third variety, lobdtum, has its fronds 

 strap-shaped below, widening at the upper part, and 

 there cut into two or more acute lobes; and a very 

 beautiful variety, multifidum, has its fronds strap-shaped 

 below, spread out at the upper part, and cut into 

 crowded, more or less blunt, and wavy lobes. A fourth 



