into spore-cases— sometimes a few pinnæ at the middle of
the frond, while the apex is leafy, sometimes the base of
a pinna, while its apex retains the leafy form, sometimes the
base of a pinnule here and there, just its apex too, being
broad and leafy ; but the usual condition is to find a few
of the shortened pinnæ, which form the apex of the frond,
contracted and soriferous throughout.
The venation, as seen, in the barren fronds, consists of
a prominent midvein, bearing once or twice forked venules
proceeding to the margin in direct lines. In the fertile
parts of the frond, only the midrib of the pinnules is fully
developed, and the spore-cases are attached to a small portion
of the venules which becomes developed just to serve
as a receptacle.. The spore-cases are subglobose, shortly
stalked, reticulated, and two-valved, opening vertically.
The Osmund Eoyal is a widely-distributed plant, occurring
in favourable localities, that is, marshy and boggy
situations, throughout the United Kingdom, and, as already
mentioned, extremely abundant and luxuriant in some parts
of Ireland. It is common throughout Europe, and occurs
in the United States of America.
This plant is especially suited, in cultivation, to occupy the
base of rock-work abutting upon a piece of water, where its
roots may be placed within the reach of the water. Eor
the margins of ponds or lakes, or for any other damp localities,
it is also well adapted; and in such situations only
does it acquire anything like its natural vigour. It should
have peat earth for its roots. The best way to establish
it IS, to procure strong vigorous patches from localities
where it abounds, and these, if removed carefully any time
before growth commences— or even after it is considerably
advanced—win succeed perfectly. This course is far more
satisfactory than to make use of weaker plants in the hope
of their eventually gaining the requisite vigour to produce
the effect desired.
Genus I. POLYPODIUM, Liimceus.
The Polypodies, which botanists call by the Latin name of
Polypodium, are known from all the other British Eerns,
by their having the spore-cases arranged in little round
patches here and there on the back of the frond, these
patches not being at any time, or at any stage of their
development, covered by the membranous film which, it
has been explained, is called an indusium; hence they are
said to be naked, or non-indusiate. This family includes