WALL RUE. 33 



Wall Rue (Asplenium ruta-murarid). 



The Wall Rue, or Rue-leaved Spleen wort, is one of the smallest 

 of our ferns, and one that is easily overlooked by the tyro. 

 Usually only two or three inches in height though in favoured 

 localities as much as six inches it does not force itself on our 

 attention, but must be looked for. Naturally, it is a sub-alpine 

 species, growing in the crevices of rocks ; but it has also taken 

 possession of many an ancient wall and bridge where the partial 

 decay of the mortar has left minute crannies into which it can 

 thrust its delicate rootlets, whilst its short scaleless rootstock 

 nestles among mosses and lichens. It is, indeed, far better 

 known as a wall-plant than as a rock-plant (Plates 28, 29). 



The general outline of the dull-green frond is somewhat 

 wedge-shaped, but it is very variable and often irregular. It is 

 evergreen, very stiff and leathery, and is twice pinnate. The 

 stipes accounts for about two-thirds of the entire length of the 

 frond, and is naked throughout its length. The pinnas have 

 stalks, and though the upper pinnae are scarcely divided, the 

 lower ones are broken up into from three to seven wedge-shaped 

 pinnules, whose broad top may be rounded or toothed. The 

 veins in the pinnules so fork that they describe a fan-shape, and 

 there is no distinct midrib. The sori form thick lines, of which 

 there are from two to five on each pinnule. The indusium 

 may have a clean cut or a ragged edge. The spores are 

 produced from June to October. 



The Wall Rue is pretty generally distributed from north to 

 south throughout these islands, though it is less frequent in the 

 eastern half of England. It is found at an elevation of 2000 

 feet in the Highlands. Specimens found on walls in the lower- 

 lying districts are always small an inch or two in length but 

 when growing from the clefts of elevated rocks, as in North 

 Wales, Derbyshire, the Lake District, and the Highlands, it 



