DISTRIBUTION AND TOPOGRAPHICAL ASPECT. 35 
in warmer regions is less great, but their influence on the 
aspect of vegetation there is of a difierent character. They 
are frequently epiphytal in the tropics, and by their varied 
forms and tints, and the way in which they fix themselves, 
they give an air of peculiar luxuriance to the higher vege- 
tation. Even in the temperate regions some of these 
herbaceous Ferns attain considerable height, as is the case 
with the common Bracken, which, in the hedgerows of 
sheltered rural lanes in the south of England, reaches the 
height of eight or ten feet, and assumes the most graceful 
habit that can be conceived. 
Wherever the Perns occur, whether they be the herbaceous 
species of temperate climates, or the arborescent species of 
the equatorial regions, or the epiphytal species which clothe 
the trunks and branches of the trees in tropical forests, 
they add a marked and peculiar character of beauty and 
luxuriance to the scenery, and that to an extent which is 
not realized by any other race of plants. 
