The Wall-rue 



grow there till we have exhausted all the forms to be 

 found on wayside and seaside rocks and walls. 



Here is an old wall running along the roadside, and 

 forming the boundary of a field. The prosaic person 

 may tell us it is in a ruinous condition, and sadly in 

 need of the plasterer's care ; but what a joy it is to the 

 fern-lover ! Peeping out from a chink between two of 

 the rough, unhewn blocks of stone is a little dark-green 

 fern. Are we sure it is a fern ? Let us put our know- 

 ledge to the test. On the back of the leaf, which is 

 only 2 or 3 inches long, we notice the sori, or clusters 

 of spore cases. " It is a fern !" we at once joyfully 

 exclaim. 



We shall now examine it more particularly. The 

 leaves, which grow in tufts, are borne on very wiry leaf- 

 stalks, which are black towards the bottom. The lower 

 leaflets (pinnae) are stalked, and are themselves divided 

 into smaller leaflets (pinnules), but not in a very regular 

 manner ; therefore we say the frond is irregularly twice 

 pinnate. The upper pinnae, however, are quite entire. 

 Each little division of the leaflet is roughly wedge- 

 shaped, and rounded and toothed at the tip ; but when 

 we are told that this is a very variable little fern, we are 

 not surprised when we meet with fronds that do not 

 quite answer to this description. The creeping stem, 

 or rootstock, as it is generally called, is short, and the 

 roots are long, to enable them to reach the food-supplies 

 in the scanty soil which has somehow managed to lodge 

 itself between the stones. 



21 



