

INTRODUCTION. 13 
especially in the case of those of creeping habit, yet they are not 
so always. 
It is in the fronds that we must seek for that ornamental character 
which renders the Ferns so popular. The fronds alone, however, 
afford an almost endless variety. Some of them are very large, 
others are very small; some are quite simple and not at all divided, 
while others are divided beyond computation into little portions or 
segmenís. It is these much-divided fronds which are generally 
Tegarded as the most elegant. Even in the few species which are 
natives of Britain, this variety of size and form is very obvious. 
There are some among our native species which are not more than 
two or three inches high, while others are five to six feet or more in 
height; and they vary from less than an inch to two feet or more 
in width, presenting great differences of outline, of which, however, 
the most common- are: the lance-shaped, the ovate, the triangular 
or deltoid, and the pentangular. Some fronds are quite simple, and 
others are cut into innumerable small segments. There is variety 
of texture, too, among the Ferns; some being so thin and delicate 
as to be almost transparent, while others are thick and leathery, 
and some perfectly rigid. And in respect to colour, while green 
predominates, some are pale green, some deep green, some have a 
peculiar glaucous or sea-green tint, and some are dark brownish 
or olive green. The surface is variously smooth and shining, or 
opaque, or less frequently, covered with hair-like scales. 
The fronds of almost all Ferns are, in their incipient condition, 
coiled up inwards towards the axis of development, forming a series 
of convoluted curves. This folding up of the fronds of Ferns, as 
of the leaves of other plants, is termed their vernation; and this 
peculiar form of vernation is that called cireinate, or gyrate. . The 
only British Ferns which have not circinate vernation, are the 
Botrychium and Ophioglossum, in which the parts, instead of 
being rolled up while undeveloped, are simply folded together, the 

