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rockwork, the conditions of its natural growth being duly borne in
mind. “ Many persons thirds,” he observes, “ that if they put the
root of the plant into soil, and water it, they have done all that is
necessary; but the wall and the rook Ferns require something moro
than this. Tho thin succulent extremities of tho wiry roots, insinuating
themselves into every crevice, and absorbing on all sides tho
scanty moisture retained by tho coarse material upon which they
vegetate, arc in removal generally left behind, and yet tho plant is
expected to live and flourish for the simple reason, that as it must
have been half starved upon the dry wall and now has plenty to
feed on, it ought to do so. The decayed mortar and the mouldering
brick, while they afford the potash, lime, and other mineral substances
necessary to fern structure, ensure the grand requisite of
drainage, and admit no accumulation of moisture beyond that which
is essential to vegetable life. Stagnant water, and especially when
lodged in soil abounding in decomposing organic matter, is fatal to
most of the species of this genus.”
In endeavouring to account for the difficulties which occur in
cultivating Ferns such as the present, which sometimes prove to ho
rather shy growers under artificial treatment, the natural conditions
under which the plant occurs should bo weU studied. Here is a
species naturally abundant and apparently free, which yet oftentimes
refuses to maintain its natural vigour under cultivation. Why is
this ? In most oases it will be found that there is something wrong
at the foundation: the roots of the plant are damaged or suffering.
Indeed, this appears to be the principal source of failure in cultivating
this species. In a natural state it grows on some perpendicular or
sloping face of wall or rook, inserting its roots into the crevices and
fissures, and there it finds enough nourishment. Even when it is
growing on banks, the soil is generally of an open sandy texture, so
that water cannot stagnate. It should, therefore, never be planted
in large masses of soü retentive of moisture ; and in planting, the
crown should be elevated between fragments of stone, the pots should
have an extra amount of drainage, and sand, or fine broken brick,
or broken sandstone, or the ruhbly portions of mortar from old bruld-
ings, should he freely used. In short, above that portion which is
kept free for drainage, the pot should be fiUed up with coarse pieces
of brick, rock, or mortar, and the interstices only filled with finer
soil, consisting of tho same ingredients, pounded or broken up, aud
mixed with a due proportion of sandy loam.
This peculiar mode of potting is suitable especially for the present
species, the Wall Rue, and the Ceterach. None of these plants,
moreover, require so much shade as other Ferns, although, if they
aro kept tolerably dry at the crown, they do not refuse to grow in
structures which are shaded for other kinds. Water must he applied
cautiously ; the crowns or centres of growth should not be wetted,
and the fronds themselves are the better for being kept dry, although
an occasional syringing, if necessary to cleanse them, will not be found
injurious, provided the fronds and the crown are afterwards allowed
to get dry. The more successful instances we have seen of the
cultivation of this Fern, were in cases in which the atmosphere of
the greenhouse was kept rather drier than is usual in structures
devoted to Fern culture.
Until lately very little variation had been observed in this species.
Besides incisum, there had been found plants in which the apex of
the frond was dichotomonsly divided, but as often occurs in otber
species, these have proved inconstant. There are now, however,
several well-marked varieties known :—
1. incisum (M.). This is the most beautiful variety yet discovered,
and is exactly analogous to the var. eambricum of Polypodium mlgare.
The fronds are of the usual outKne, pinnate. The pinnæ have a
tendency to become triangular, and in some of the best forms of the
variety are nearly uniformly so, with acute apices ; they aro deeply
pinnatifid, the segments narrow oblong or elKptic, usually acute, and
irregularly sometimes deeply serrated, the larger ones not unfrequently
lobate. It has been found in several looaKties, namely—
Devonshire, Pev. W. 8. Hore. Lancashire : Kant Clough, near
Burnley, 8. Oibson. Yorkshire : Smeerset, near Settle, J. Tatham,
A. Clapham. Cumberland : Borrowdale, Miss Wright. ? Clare, J.
P . Kinahan. Jersey, Sherard, according to Plukenet. The Settle
form, as communicated to ns from Mr. Clapham’s garden, is the
finest we have seen. In this the more perfect pinnæ sometimes
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