THE SPL&ENWOKTS. 
walls the finest specimens are always those which 
are found at the top of the walls, just beneath the 
coping-stone or crowning bricks, which serve as a 
protection for the crown of the Wall Rue. Between 
the bricks of walls and in the crevices of rocks the 
little Fern inserts its wiry fibrous rootlets, which 
suck in the moisture pent by the stony covering, 
and revel in the combination of old mortar and 
deposits of leaf-mould formed by dropping leaves. 
The Wall Rue prefers to grow — root-stock, crown, 
and rootlets, — -horizontally, a position rendered 
necessary by the habit of the little plant in growing 
between the mortar lines of walls. From its tufted 
crown the tiny fronds shoot out in dense clusters. 
Stem and leafy part are usually about equal in 
length. The tiny branches of the frond are placed 
alternately on each side of the rachis, each branch 
being again divided into little diamond-shaped 
lobes. These lobes are thick and leathery in tex- 
ture and of a dark, shining green colour. When 
the spores ripen the clusters of spore-cases 
usually become confluent, so that in the autumn 
the backs of the leaflets are thickly covered wdth 
rich brown masses of seed. Evergreen in 
37i 
