112 FILICES 
the common stalk of the frond. They spread loosely, and are moved by the 
slightest wind, the middle branch being the largest. Each branch is pinnate 
at the base, and pinnatifid at the upper part; the pinne are also pinnate at 
the base, and pinnatifid and gradually tapering at the top, the edges near 
the point being undivided, the pinnules and lobes oblong and obtuse. The 
pair of pinnules at the base of each pinna, close to the mainstalk of the frond, 
are so nearly of a size, and so placed, that when the pinne are exactly 
opposite, they stand in the form of a cross ; the two nearest the summit of 
the branch being smaller than the two opposite, and more nearly in a line 
with the rachis. There is an angular bend in this fern, just at the point of 
the rachis where the side branches rise. 
A mid-vein winds through each lobe or pinnule, and the lateral veins 
are usually alternate and without branches. Each terminates at the margin, 
and the clusters of fructification, which are circular and of pale brown, are 
placed at its extremity. Sometimes the clusters are densely crowded; in 
other specimens they are scattered and remote. A large number of the 
fronds are barren, and the fertile ones are generally taller than those without 
fructification. 
The Three-branched Polypody is not infrequent in moist woods, and in 
stony, barren, mountainous places both in England and Wales, excepting 
that part of England which lies eastward of Derbyshire, Gloucestershire and 
Devonshire. It is common in Scotland, and is very generally distributed, 
being found in every country of Europe. Its underground stem is slender, 
black, wiry, and creeping to a great distance. This fern is by Mr. Newman 
termed Gymnocarpium dryopteris, The dried specimen of the Herbarium, 
though preserving well the outline of this fern, gives no idea of its attitude 
while living. This is gently drooping, not only the whole leafy portion 
bending down, but the lobes curving down also. 
4. Limestone Polypody (P. calcérewm).—Fronds triangular, some- 
what three-branched, lower branches pinnate, the pinnz pinnatifid, blunt, 
the uppermost nearly entire; fructification marginal. This plant is also 
known as Smith’s Polypody, or Rigid Three-branched Polypody. Notwith- 
standing, however, its latter name, it is far less distinctly three-branched 
than the last species, and is very different from it in its habit. The lower 
branches are much smaller in proportion to the middle one, and all are erect 
and rigid. It has not either, in any great degree, the angular bend in the 
stalk of the frond which so well characterizes the Oak Fern, though it in - 
some specimens slightly shares this peculiarity. It is also a more rigid and 
firm plant, of a darker, duller green ; its stalk is more scaly at the lower 
part, and green instead of purple ; its clusters of fructification are usually 
more densely crowded; it has also a marked distinction in the mealy 
appearance presented by the surface, owing to numerous stalked glands 
which crowd over every part of it. The fronds are from six inches to a foot 
high, nearly triangular, the base shorter than the sides. The stalk is of 
about the same length as the leafy part; but the side branches are not only 
shorter, but are more slender than the middle one. The lower branches are 
pinnate, and the pinne are cut down nearly to the mid-rib ; the upper branch 
is pinnate, with its lower pinn again pinnate, and the upper ones pinnatifid, 
