22 
HISTORY OF BRITISH FERNS. 
The Ferns belong to the lowest group of vegetation, 
which is especially remarkable for its loose and often 
succulent texture, owing to the absence, or nearly so, of 
those tissues which give firmness and elasticity to the 
higher orders of plants. The Ferns, however, are the 
highest members of this group, and hence we find them 
possessing, to some extent, both woody and vascular tissue, 
— matters which, together with cellular tissue, the soft 
loose material above mentioned, may be found explained 
in any elementary book on physiological botany. 
Taking now a retrospective glance, we have seen that 
the Ferns are, as regards external structure, flowerless 
plants, having erect or creeping stems, which bear the leaf- 
like fronds ; and on some part of the surface of the latter, 
usually the lower side, but sometimes the margin, are borne 
the clusters of seeds, which, in the majority of the native 
species, are, when young, furnished with a membranous 
scale-like cover. 
