i8 
THE FERN WORLD 
ditions of growth are favourable, until the stem of the Fern 
is raised, as in the gigantic cryptogamic growths of the 
forest, to a height of as much as fifty feet. And from the 
crown of the plant at this height continue to be thrown out, 
as before, a beautiful circlet of fronds. There are some 
British Ferns which exhibit this same tendency to an 
elongation of the caudex, and one species exhibits a tree-like 
stem, which is often raised two feet or more from the ground. 
But the absence of the extreme heat and moisture of tropical 
climates prevents the stems of the majority of our native 
Ferns from exceeding the moderate length of two or three 
inches. From the crown of the caudex, and from various 
points along the upper side of the rliizoma — in Ferns with 
creeping stems — spring the fronds. These consist of two 
distinct parts, which may be generally likened to a stalk and 
a leaf. What would correspond in an ordinary plant to a 
stalk is in Ferns named a stipes — plural stipides — whilst 
the upper portion, or the leafy expansion, is carried upon an 
extension of the stipes called a rachis — plural ret chide.*. 
In compound fronds the continuation of the stipes, or the 
mid-rib of the frond, is called the primary rachis. If the 
leaf be divided, with divisions having mid-ribs branching 
out on each side from the rachis, these mid-ribs become each 
a secondary rachis. We return, however, to the stipes, or 
stalk, of the frond. There is very considerable variety in 
the length and appearance of the stipes in the various kinds 
of Ferns. Sometimes it is so short that the lower leafy 
portion of the frond almost touches the crown of the root- 
stock. Sometimes it is of considerable length, and indeed 
there are varying and intermediate degrees of length in the 
different species. The colour and thickness also vary. 
Sometimes the stipes is thin and delicate; sometimes stout 
and fleshy. In some species it is bared of any covering; in 
others it is densely or sparsely covered with various-coloured, 
