BRITISH FERNS. 33
Polypodium fragile of Liuueus and other authors, iu its most
common form, appears to be the Cystea fragilis of Smith, and is
represented iu Sowerby’s English Botany, pi. 1587, and in
Bolton’s Filices, pi. 45. As Sir J. E. Smith has taken more
pains with this genus than any other of our authors, I shall give
his descriptions at length, accompanied iu every instance by the
figure of a frond, carefully compared with the specimens from
which the description is compiled.
Cystea dentata. Smith. Polypodium dentatum, Dickson. Rather
smaller than Cystea fragilis, hut agreeing
with it in texture, colour, and general aspect.
Rhizoma tufted, small. Frond for the most
part correctly bipinnate, a few of the lower
pinnæ only, in luxuriant specimens, being
pinnate or pinnatifid ; the pinnulæ are exactly
ovate, or rounded, obtuse, pointless,
copiously and bluntly serrated or toothed :
their ribs wavy; their base not decurved,
though seated on a winged midrib ; masses
prominent, at length entirely confluent, of a
uniform rich chestnut brown. I do not perceive
in the younger ones that peculiar blackness
which is observable in P. fragilis. The
cover is short, jagged, and concave. I have
never seen it in an early stage before bursting.—
Eng. Flora, iv. 300.
Sir J. E. Smith has described this species,
as far as regards the leading characters of the
fronds, with great accuracy ; hut he has made
his species too lax by introducing into it a
variety of specimens from Llangollen and
Anglesea, which have nothing to do with
Dickson’s plant. The original plant is solely
Scotch, and is the only form of fragilis which
I could find on the northern shoulders of
Ben More, where it is most abundant, descending
even to the walls on the road side between Killin and
Tyndrum. Sir J. E. Smith appears to have known nothing of
the plant but from a dried frond : he makes no allusion to the
reflexed, drooping, and convex pinnæ of the young fronds, or the
more marginal arrangement of the sori, the only characters about
the plant which can he considered specific : indeed so striking
were these characters to me, that I quite believed it a species
until I had obtained an intermediate series of forms.
The next variety I consider to be the typical form of P. fragile,
as described by Linneus.
Cystea fragilis. Smith. Fronds several
together, from four to ten or twelve inches
high, lanceolate, pointed, smooth, of a full
though bright green, doubly or almost
triply pinnate. Rachis brown or blackish,
very brittle and juicy, occupying one-
third or nearly half of the length of the
whole, destitute of scales, except at its
very base. The pinnæ are usually nearly
opposite, acute, and of a moderate length ;
the pinnulæ mostly alternate, ovate, acute,
or pointed ; their base always tapering
and decurrent; they are by no means
linear or oblong, nor is their margin wavy,
but copiously, deeply, and sharply toothed,
and their substance is firm ; the lower and
larger ones are deeply pinnatifid, their
lobes resembling the upper pinnulæ.
Masses numerous and crowded, globular;
at f r s t pale, but fn a lly blackish and confluent,
covering the whole back of the
frond. Indusium white, flaccid, membranous,
concave, irregularly jagged and
torn, sometimes lengthened out into an
oblong point, but soon turned back and
, obliterated, or forced off by the swelling,
shining thecæ, which, in an early state,
are often quite black, though subsequently
browner.—Eng. Flora, iv. 299.
In this description a discrepancy occurs in the colour of the
thecæ ; the colour of the masses, in an early state, is very inconstant,
hut generally blackish ; the autumnal fronds, when in
cultivation, have smaller masses than the vernal, the masses also
are rarely confluent, the frond itself is more minutely divided.
I now proceed to a plant of very remarkable character, and one
which at first sight would perplex many an able botanist ; and
E