FERNS AND THEIR RELATIVES 87 
appearance. The hood seems to be represented by a 
thickening of the vein, alongside which le the spore- 
cases. Old walls and ruins generally are a_ happy 
hunting-ground for this fern, and they should always 
be examined carefully by the plant-hunter, who will find 
a rich reward therein. 
The last group of typical ferns is one very clearly 
marked out and very easily remembered. The shape 
of the hood need not be kept in mind, for the spore- 
cases never have any, but are left 
naked. In this section are the 
Polypodies, in which the spore- 
cases are arranged in circular 
patches like those of the Male 
Fern, but are left exposed from 
the very start. The Common 
Polypody grows very abundantly, 
and the peculiar shape of the frond, 
segmented into rows of fingers, 
serves to distinguish it. The Oak 
and Beech Fern, on the other hand, 
have much-divided fronds, and are 
not so soon recognised. They may 
be traced to their lair, however, by 
the fact that the fronds are not 
jointed to the stem, but are con- 
tinuous in structure with it. When 
the fronds die, therefore, parts of 
them continue to cling to the plant. 
The Oak Fern has a unique pecu- 
liarity. Each frond branches off into three parts of about 
equal size, the parts themselves being very much divided, 
and the whole giving a fan-like appearance. 
COMMON POLYPODY. 
