20 
BRITISH FERNS. 
the soil the food which the plant requires for its 
nutrition. 
The stem of a fern consists of a mass of tissue, from 
which the stalks of the fronds proceed upward, and 
the root downward. In British ferns, these stems 
seldom rise up into the air, but are either buried in 
the earth, or lie prostrate upon it: in the common 
polypody and the spleenwort they attain a consider¬ 
able size. When out of the ground, they are covered 
with scales and hairs, and present a very shaggy 
appearance. In some cases, as in the Common Brakes 
and the Flowering Fern, the stem rises erect in the air, 
and bears its fronds in the same way as higher plants 
bear their leaves. It is in tropical ferns that these 
stems attain their greatest size, and rise above the 
ground forty or fifty feet in height. Such ferns are 
called tree-ferns. But the nature of this stem is the 
same in all cases: it consists of a mixture of woody 
and cellular tissue, constituting the basis of the fronds ; 
and in cases where the stem is perennial, it consists of 
the remains of the successive annual developments of 
the fronds. 
The fronds vary much in form, and the stalk on 
which they are placed is called the stipes. They 
vary in size, and also in duration: they usually, how¬ 
ever, come up in the spring, and lie down in the 
autumn. 
The frond, like the leaf, is divided into the blade 
and stalk, or stipes. The woody tissue of which 
