r i'
G4
attached on the concave side of the mass. The detached
pinnula on the left hand at the bottom of the cut shows the
veins, with the masses and their indusia in situ ; that ou the right
hand shows only the veins and the attachments of the thecæ. In
approaching maturity the indusia are forced aside and ultimately
lost, the masses becoming circular, as represented in the detached
pinnula at the top of the cut, and often indeed confluent,
covering the entire under-surface of the pinnula.
Professor Don, in the Transactions of the Linnean Society,
Vol. xvii. p. 436, observes, that “ there are two very marked
varieties of this plant, the one with broader segments of a dark
green, and with the rachis of a pale purple hue ; the other, and
that the commonest, with the segments of
a more delicate texture, and the whole
frond of a pale green. The latter variety
varies much in size, according to soil and
situation ; in damp, shady places, it becomes
the Filix-femina of English Botany,
and ill more open exposed situations, the
irriguum ; but neither of these states is entitled
to he regardedas a distinct form.” In
these remarks. Professor Don has omitted
to mention a character which I think
of still more importance ; the variety, of
which “ the segments are of a more
delicate texture,” has the margins of each
pinnula folded together, and so convolute
as nearly to meet below, which character
causes each pinnula to look very narrow
from above : the pinnulæ of the other
variety are spread out and flat ; the serratures
or lobes being perfectly displayed.
The Aspidium irriguum of Smith is a
variety of the convolute form ; it is not one
of those types of form which in P. aculeatum, L. dilatata, &c. are
constant in their peculiarity through a whole series of plants ;
the characters given by Smith of “ small size,” “ more lanceolate
figure,” “ main stalk occasionally scaly and exactly quadrangular,”
“ leaflets shorter, less linear, deeply serrated, or
partly pinnatifid,” may correctly describe one frond, or one
plant, hut they are not characters by which to distinguish any
type of form or series of plants ; and the name irriguum being
founded on these characters, cannot, with propriety, he retained
even as a variety, because, should it hereafter be proved that we
possess two or more species of Athyrium in this country, we
shall inevitably find the above characters applying occasionally
to a frond or plant of every species, and thus we shall have
varieties of more than one species named irriguum.
Filix-femina may be said to possess two distinct types of form,
which, although they may occasionally approach, yet, in ninety-
nine plants out of every hundred, in a recent state, may he distinguished
at a single glance : they may be thus characterised :—
1. Flattened type; the fronds are broad, drooping, heavy,
and often of very large size, three, four, and five feet in length ;
the pinnulæ are perfectly flat, and all their cuttings are clearly
displayed, and the masses of thecæ seldom, perhaps never, become
perfectly confluent ; the plants of this type vary infinitely in the
cutting of the pinnulæ, also in the colour of the rachis, which is
green, or inclining to red, purple, or even brown ; this form is
figured at page 63, and is the Polypodium rhæticum of Linneus.
2. Convex type ; the fronds are narrower, rigid, erect, light,
feathery, and of smaller size, hut still occasionally reaching two
feet to thirty inches in height ; the pinnulæ are convex, the
margins always being bent downwards, the masses crowded and
confluent ; the rachis is somewhat pellucid, and very brittle ; it
is generally pale green, sometimes nearly white, sometimes of a
pink tinge, and sometimes almost as red as coral ; this form is
figured at page 64, and is the P. Filix-femina of Linneus.
I
:l ;
ii::
I i ri'
' i l l