fronds of this kind of Eern produce fructification, which,
however, is usually confined to the upper half of the fronds,
and has generally become mature by the end of September.
The most important variety is the Welsh Polypody, called
Polypodium cambricum by Linnseus. In this the lobes of
the frond are broader, and,'instead of being simple, are
deeply and irregularly lobed a second time, the segments
being rather sharply toothed. This form, which is certainly
only a variety of the common Polypody, is almost
always found without fructification. Under slight shelter,
where its fronds are persistent, it is one of the most beautiful
of what are called hardy Eerns.
Other varieties which have been proposed are— bifidum,
in which the lobes are more or less regularly two-cleft at
the apex; serratum, in which they are deeply saw-edged;
and acutum, in which they are drawn out to a long narrow
point. The forms, however, are not constant, and are hence
of but small importance.
The species and its varieties grow freely under cultivation,
either planted in pots, or on rock-work in a shady
situation.
Genus V. POLYSTICHUM, Eoth.
The Polystichums form a small and very distinct group of
evergreen Eerns, some forms of which rank among the most
beautiful of our native species. They once formed part of
the genus Aspidium, the token of admission to which, was
the presence of round seed-patches covered by a scale.
Erom the allied genus Lastrea, the Polystichums are known
by their having the scale-like cover of the sori circular,
without a lateral notch, its attachment being by a httle
stalk in the centre: this form is called peltate. To a practised
eye they are also known by a more rigid texture, and
by having altogether a more spiny appearance than even the
spinulose species of L astrea; but these means of recognition
the novice can turn to but little account. The alpine form
of the genus is strictly evergreen, and the others acquire this
character when in a sheltered situation, but if they are much
exposed, the fronds will be killed by a sharp frost. In
general, however, they retain their fronds without much disfigurement
from frost, quite through the autumnal quarter,
and often far into winter. The British species of Polystichum
are three in number.
The name Polystichum is compounded of two Greek
fit