32 BRITISH FERNS. 
conditions as to moisture, &c., were maintained. As 
a natural sequence, we might expect to find that 
after the base of the trunk had thoroughly decayed, 
the action of wind and other causes would be con- 
tinually throwing down these Tree Ferns in a state 
of nature: and so it is; their prostrate trunks en- 
cumber the ground in all directions; the growing 
extremity often continuing to develope its convolute 
fronds, even when the trunk is prostrate on the 
earth. 
The second portion of a fern has some analogy 
with the trunk of a tree; it is sometimes erect and 
trunk-like, as in the Tree Ferns, to which I have 
just been alluding; sometimes merely an almost 
globular mass placed erect in the earth; and some-~ 
times a creeping, rootlike stem, which either climbs 
trees and rocks in the manner of ivy, or creeps in 
a horizontal direction under ground, in the manner 
of what is called “couch-grass,” sending up a leaf 
here and there to develope itself above the surface. 
I have already stated that it is called “caudex,” 
*cormus,” or “rhizome,” according to its position 
and character; but in any state, and under any 
