STRUCTURE. 5 
been objected to as being unnecessaiy, that of leaf being 
employed in its stead. The peculiar manner, however, in 
which the fructification is borne on this part of the plant, 
seems to render it desirable to maintain a distinctive name. 
An analogy has been traced between the fronds and the 
deciduous branches of other plants , but this does not hold 
good, because though the fronds are in some cases articu- 
lated with the stem, especially in those of creeping habit, 
yi t they are not so always. In their incipient condition, 
the fronds of almost all ferns, are coiled up inwards to- 
wards the axis of development, forming a series of con- 
voluted curves, or bent like the head of a crozier. The 
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 called circinate. The only British species 
which differ in their vernation, are the Botrychium and 
the Ophioglossvm, and in these the parts, instead of being 
rolled up while undeveloped, are simply folded. The more 
compound of the circinate species have the divisions of 
the frond also rolled up in a similar manner: in this case, 
the larger divisions first open, and the rest afterwards, in 
order. In many species, the partially developed fronds 
have a very peculiar and graceful appearance. 
When the fronds become fully developed two parts are 
distinguishable. At the base, more or less extending 
upwards, is a leafless portion, which is called the stipes 
or stalk, or sometimes by error the stem, the latter term 
properly belonging to the caudex. The lower part of the 
stipes, generally, and sometimes even the entire length of 
the rachis, which is the continuation of the stipes through 
the leafy portions of the frond, is more or less densely 
covered with paleaceous or membranous scales ; in some 
cases confined to a few small bodies, scattered sparingly 
near the base of the stipes, but in other cases so large and 
numerous as to produce a shaggy surface. These scales 
are most generally regarded as portions of disrupted epi- 
dermis ; but whatever their origin, they must be regarded 
as special organs, being very constant in their appearance 
