16 Origin of the British Flora. 
ancient forests, partly because of the extensive planting, 
which has introduced trees belonging to other districts 
and has profoundly modified our woodland flora. To take 
one or two instances, the Hornbeam is one of the principal 
ancient trees of Essex and other south-eastern counties; 
but in the New Forest it only occurs sporadically, near 
houses and villages, and such would seem to be its ordinary 
mode of occurrence in most parts of Britain. We cannot, 
however, say positively that it can only be reckoned as 
indigenous over a certain limited area, though the evidence 
points in that direction. The Scotch Pine is equally 
doubtful, for it was abundant throughout Britain when 
our existing peat-mosses began to form; it afterwards 
disappeared throughout the south of England; but now 
that it has been re-introduced it seeds freely and is fast 
spreading, especially in Hampshire and Dorset. It is 
probable that as far back as Roman times trees were 
planted round the villas for shade and beauty, and Roman 
officers would probably have given preference to southern 
forms which reminded them of their native lands. Thus 
such trees as the Horse Chestnut, Spanish Chestnut, 
Sycamore, Lime, and probably the Vine and Fig-tree, 
would be introduced. Some of the trees died out, others 
established themselves from seedlings and still remain; 
but except through the negative evidence of the geological 
record there seems to be no satisfactory way of telling 
which of our rarer trees were thus introduced. 
Besides the forest-trees, we have a large number of 
plants which are confined to woods; we have also several 
species of land-snails, which are similarly restricted to 
ancient forest and are not found in modern plantations. 
The moisture and shelter of our woods make the general 
character of the undergrowth fairly uniform throughout 
Britain; though we possess a large number of woodland 
