[Illustration: ]
ASPIDIUM MARGINALE, Swartz.
Evergreen Wood-Fern.
Aspidium marginale:—Root-stock ascending, stout, shaggy with long
shining-brown chaffy scales; stalks rather stout, a few inches to a foot
long, more or less chaffy with shining scales; fronds standing in a
crown, one to two feet long, evergreen, sub-coriaceous, ovate-lanceolate,
scarcely narrowed at the base, pinnate or sub-bipinnate; pinnæ almost
sessile, the lowest ones broadest, unequally triangular-lanceolate, the
middle ones lanceolate-acuminate, slightly broader above the base;
pinnules or segments smooth and dark-bluish-green above, paler and
sometimes slightly chaffy beneath, adnate to the narrowly winged
secondary rachis, oblong or oblong-lanceolate, often sub-falcate, varying
from crenately-toothed to pinnately-lobed with crenulate lobes, obtuse or
sub-acute, those next the main rachis sometimes distinct, short-stalked,
sub-cordate at the base and with rounded auricles; veins free, forked or
pinnately branched into from two to five curved and usually conspicuous
veinlets; sori rather large, placed close to the margin of the segments;
the orbicular-reniform indusia firm in texture, convex, smooth, often
lead colored.
_Aspidium marginale_, Swartz, Syn. Fil., p. 50.—Schkuhr, Krypt. Gew., p.
195, t. 45, _b._—Willdenow, Sp. Pl., v., p. 259.—Pursh, Fl. Am.
Sept., ii., p. 662.—Link, Fil. Hort. Berol., p. 107.—Hooker, Fl.
Bor.-Am., ii., p. 160.—Torrey, Fl. New York, ii., p. 495.—Gray,
Manual, ed. ii., p. 598.—Mettenius, Fil. Hort. Lips., p. 92;
Aspidium, p. 55.—Eaton, in Chapman’s Flora, p. 595.—Robinson, Ferns
of Essex Co., in Bull. Essex Inst., vii., No. 3, p. 50.—Williamson,
Ferns of Kentucky, p. 97, t. xxxv.—Davenport, Catal., p. 32.
_Polypodium marginale_, Linnæus, Sp. Pl., p. 1552.
_Nephrodium marginale_, Michaux, Fl. Bor.-Am., ii., p. 267.—Hooker, Sp.
Fil., iv., p. 122.—Hooker & Baker, Syn. Fil., p. 273.
_Lastrea marginalis_, Presl, Tent. Pterid., p. 77.—J. Smith, Ferns, Brit.
and Foreign, p. 157.—Lawson, in Canad. Naturalist, i., p. 281.
_Dryopteris marginalis_, Gray, Manual, ed. i., p. 632.—Darlington, Fl.
Cestrica, ed. iii., p. 396.
Hab.—Rocky hill-sides in rich woods, especially where black leaf-mold
has gathered between masses of rock; one of our most abundant and
characteristic ferns, confined to North America, but extending from New
Brunswick to Central Alabama, Professor Eugene A. Smith; westward to
Arkansas, Professor F. L. Harvey; Wisconsin, Parry, T. J. Hale; and
brought from the Saskatchewan and the Rocky Mountains of British
America by Drummond.
Description:—Professor Robinson has remarked of this species:—“This comes
nearer being a tree fern than any other of our species; the caudex,
covered by the bases of fronds of previous seasons, sometimes resting on
bare rocks for four or five inches without roots or fronds.” The
root-stock is much like that of _A. Filix-mas_, being very stout-closely
covered with persistent stalk-bases and very chaffy. The chaff really
grows mainly on the bases of the stalks, or covers the closely coiled
buds which crown the root-stock. It is composed of shining
ferruginous-brown thin lanceolate acuminate scales fully an inch in
length, and destitute of a thickened midnerve. The fronds grow in elegant
crowns from the apex of the root-stock, some six or eight or perhaps ten
to a plant. The stalks vary in length, but are seldom more than a foot
long. They are rather stout, round, but with a slight furrow in front,
commonly reddish-brown in color, fading when dry to straw-color, and
contain five or seven roundish fibro-vascular bundles, of which the two
anterior ones are largest, and the next two the smallest.
The outline of the fronds is ovate-lanceolate, varying to
oblong-lanceolate. The frond is commonly not quite so wide at the base as
in the middle, though in small specimens the base is often the widest.
The texture is thicker than in any other of our Wood-ferns, and the
fronds are fairly evergreen, not withering until the next year’s fronds
begin to uncoil. In cutting, the fronds vary from pinnate, with
pinnatifid pinnæ and short nearly entire lobes, to twice pinnate, with
pinnately-lobed segments. In the example selected for our plate the
pinnules are oblong, obtuse and crenulate, or at most, crenately-toothed.
Other, and perhaps no larger, fronds will have most of the pinnules twice
or even thrice as long as these, ovate-lanceolate and pointed, narrowed
to a sub-cordate and obscurely-stalked base, and deeply pinnately-lobed.
This is var. _elegans_ of Professor Robinson. Professor Lawson has a var.
_Traillæ_, which has “very large bipinnate fronds, all the pinnules
pinnatifid.” A very common form noticed by Mr. L. M. Underwood in
Bulletin of the Torrey Botanical Club, has fronds only four or five
inches long, the lower pinnæ only pinnatifid and the upper ones lobed,
the sori mostly solitary on the lobes.
The veins and veinlets of the frond are very distinct, being marked by
depressions in the upper surface in the living fronds, and visible as
dark lines in the dried specimens. The veins fork near the midvein; the
upper branch may be fertile at its tip; the lower branch is either
simple, or forks a second, and perhaps a third time. All the veinlets are
curved. On account of the venation Presl referred this plant to his
section _Arthrobotrys_.
The sori are close to the margin of the lobes, and vary from one to
twelve to a lobe. They are very large and prominent, and have firm
lead-colored orbicular-reniform indusia, which are slightly incurved
round the edge, and depressed at the sinus. As the fronds mature the
indusia become brownish. The spores are ovoid-reniform and have a narrow
crenulate wing.
WALKING-LEAF.
PINNATIFID SPLEENWORT.
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CAMPTOSORUS RHIZOPHYLLUS, Link.
Walking-Leaf.
Camptosorus rhizophyllus:—Root-stock short, creeping or ascending; stalks
tufted, slender, flaccid, green, but becoming brown near the base; fronds
a few inches to a foot long, sub-coriaceous, evergreen, smooth, gradually
narrowed from a deeply cordate and auricled base to a long and very
slender prolongation, decumbent and often rooting at the end; veins
reticulated near the midrib, and having free apices along the margin;
sori elongated, variously placed on either side of the veins, often face
to face in pairs, or extending around the upper part of the meshes;
indusium delicate.
_Camptosorus rhizophyllus_, Link, Hort. Berol., ii., p. 69; Fil. Sp.
Hort. Berol., p. 83.—Presl, Tent. Pterid., p. 121, t. 4, fig.
8.—Hooker, Gen. Fil., t. 57, C; Fil. Exot., t. 85.—Gray,
Manual.—Darlington, Flora Cestr., ed. iii., p. 393.—Mettenius, Fil.
Hort. Lips., p. 67, t. 5, fig. 6.
_Asplenium rhizophyllum_, Linnæus, Sp. Pl., p. 1536.—Swartz, Syn. Fil.,
p. 74.—Willdenow, Sp. Pl., v., p. 305.—Michaux, Fl. Bor. Am., ii.,
p. 264.—Bigelow, Fl. Boston.
_Antigramma rhizophylla_, J. Smith, in Hook. Journ. Bot., iv., p. 176;
Ferns, British and Foreign, p. 226.—Torrey, Fl. New York, ii., p.
494, t. 159 (_Asplenium_).
_Scolopendrium rhizophyllum_, Endlicher, Gen. Pl., Suppl. i., p.
1348.—Hooker, Sp. Fil., iv., p. 4.—Hooker & Baker, Syn. Fil., p.
248.
Hab.—On mossy rocks, especially limestone. Not uncommon from Canada to
Virginia and Alabama, and westward to Wisconsin and Kansas. It occurs
in many places in Western New England, but is rare to the east. It has
lately been found a few miles from Boston; but there is a doubt whether
the station is truly natural.
Description.—The walking-leaf is usually found in patches of considerable
extent. It seems to prefer mossy calcareous rocks, and the finest
specimens are usually firmly rooted in the crevices. In Cheshire,
Connecticut, it grows freely on moist cliffs of sandstone bordering a
deep ravine; and in Orange, in the same State, it is found on scattered
ledges of serpentine. The root-stock is very short, but creeping: it
bears a few dark-fuscous scales, and is covered with the remains of
decayed stalks. A few fronds grow from the end of the root-stock, and are
supported on slender herbaceous stems a few inches long. A transverse
section of the lower part of the stalk is semicircular, and shows a very
slender triangular central thread of dark sclerenchyma, with two somewhat
roundish fibro-vascular bundles close beneath or behind it. A section
higher up shows that the stalk is there narrowly winged on each side, and
the two fibro-vascular bundles have coalesced into one of a
roundish-triangular shape. The frond is long and narrow, and rarely rises
erect, but usually is decumbent or reclined in position.
The wings of the stalk widen out into a wedge-shaped base, which is
sunken in a sinus between two basal auricles of the frond. These auricles
are scantily developed in small fronds; but in larger ones they are more
or less prominent, making the base of the frond either cordate or
hastate. In specimens from Cheshire, Connecticut, and in some from
Indiana, the auricles are drawn out into slender points, in one instance
fully four inches long. The fronds are deep-green in color, and
sub-coriaceous in texture. The fronds of mature plants are from six to
twelve, or even fifteen, inches long; and their greatest width, measured
just above the auricles, is about one-twelfth of the length, or from six
to fifteen lines. The midrib is a little paler than the rest of the
frond, and is rather prominent on the under surface. The margin of the
frond is gently undulating or entire, rarely incised.[2] The upper part
of the frond is scarcely wider than the stalk, and commonly produces a
proliferous bud at the apex, where it very frequently takes root, and
develops a new plant. In this way a single plant in a favorable position
will become a whole colony in a few years’ time.
The venation is peculiar, and the disposition of the sori depends mainly
on the peculiarities of the venation. Dr. Endlicher’s description of them
is so clear, that it is well to repeat it here: “Veins anastomosing
[i.e., reticulating] in two series of hexagonal areoles [meshes], the
angles of the marginal areoles sending out free, simple or forked,
veinlets. Sori linear, solitary in the costal areoles [those nearest the
midrib] and on the marginal veinlets: the indusium of the latter free
toward the margin of the frond; of the former, toward the costa. In the
areoles of the second series the sori are opposite: the indusium of the
lower one free toward the costa; of the other, in the opposite
direction.” To this it may be added, that in some of the areoles the two
sori meet and are confluent at the outer angle of the areole; and in this
case the two indusia are sometimes, though not always, united into one.
The indusia of the areoles next the midrib are also often bent at an
angle, and the two portions plainly united. It was from this condition of
some of the sori that the genus was named _Camptosorus_ (bent fruit-dot);
and it is only on this peculiarity that the genus can be kept separate.
The indusium is thin and delicate, composed of sinuous-margined cellules,
and is more or less wavy along the free edge. The spores are ovoid, and
have a crenated pellucid wing-like margin.
Sir W. J. Hooker referred the _Camptosorus_, together with the species of
_Antigramma_, and the very peculiar Mexican fern _Schaffneria_, to the
genus _Scolopendrium_; making the distinctive character of the genus to
rest on the sori being “in pairs, opposite to each other, one originating
on the superior side of a veinlet, the other on the inferior side of the
opposite veinlet or branch.” In this he was essentially anticipated
twenty years by Dr. Endlicher; to whom, however, _Schaffneria_ was
unknown.
It is by no means impossible that future botanists will refer all these
species to the old Linnæan genus _Asplenium_; for it is now pretty
generally admitted that differences in venation do not constitute valid
generic distinctions, and a radicant bud on the frond is common in many
undeniably genuine _Asplenia_: and since _Diplazium_, with double
involucres placed back to back on the same vein, is inseparable from
_Asplenium_, it is by no means impossible that _Scolopendrium_ and
_Camptosorus_ should be thought to have no better claim to rank as
genera.
Probably the earliest notice of the walking-leaf is in Ray’s “Historia
Plantarum,” vol. ii., p. 1927, published in 1688. It is there called
“Phyllitis parva saxatilis per summitates folii prolifera.” Other early
accounts may be found in the “Species Plantarum” of Linnæus and of
Willdenow, and in the second edition of Gronovius’s “Flora Virginica.” In
the latter work it may be seen that Gov. Colden long ago described the
auricles as being “also often acuminate.”
A second species, with membranaceous fronds acute at the base (C.
Sibiricus), occurs in Northern Asia, but is apparently very rare.
ASPLENIUM PINNATIFIDUM, Nuttall.
Pinnatifid Spleenwort.
Asplenium pinnatifidum:—Root-stock short, creeping, branched; stalks
numerous, clustered, brownish near the base, green higher up; fronds six
to nine inches high, herbaceous or sub-coriaceous, mostly erect,
lanceolate-acuminate from a broad and sub-hastate base, pinnatifid; lower
lobes roundish-ovate or rarely caudate, sometimes distinct, the margin
crenated, the upper ones gradually smaller and more and more adnate to
the winged midrib; the uppermost very short, and passing into the
sinuous-margined long acumination of the frond; veins dichotomous or
sub-pinnate and forking, free; sori few on the lower lobes, solitary on
the uppermost, those next the midrib occasionally diplazioid.
_Asplenium pinnatifidum_, Nuttall, Genera of N. Amer. Plants, ii., p.
251.—Kunze, in Sill. Journ., July, 1848, p. 85.—Gray,
Manual.—Eaton, in Chapman’s Flora of Southern U. S., p.
592.—Hooker, Icones Plantarum, t. 927; Sp. Fil., iii., p.
91.—Mettenius, Fil. Hort. Lips., p. 72, t. 10, figs. 1, 2;
Asplenium, p. 126.—Hooker & Baker, Syn. Fil., p. 194.
_Asplenium rhizophyllum_, var. _pinnatifidum_, Muhlenberg, Catalogus
Plant. Am. Sept., ed. ii., p. 102.—Barton, Compendium Floræ
Philad., ii., p. 210.—Eaton,[3] Manual of Botany, ed. iii., p. 188,
etc.—Torrey, Compendium, p. 383.
Hab.—Discovered by Thomas Nuttall in crevices of rocks along the
Schuylkill River, near Philadelphia; also found along the Wissahickon
Creek in the same vicinity. Lancaster County, Pennsylvania, Prof.
Thomas C. Porter. On moist cliffs of sandstone in the Cumberland
Mountains, East Tennessee, Prof. F. H. Bradley. Hancock County,
Alabama, Hon. T. M. Peters. Mine-la-Motte, Southern Missouri, on
sandstone rocks, Dr. Engelmann.
Description.—The root-stocks of this little fern are creeping, branched
and often entangled, and chaffy with narrow lance-acuminate dark-fuscous
scales. The cellular structure of these scales is similar to that of the
scales of _A. ebeneum_, the cells being oblong-rectangular, and arranged
in straight longitudinal rows. The stalks are from two to four inches
long, and slightly chaffy when young: they are brown and shining at the
base, but green higher up, except that a narrow line of brown is
continued up the under side of the stalk nearly or quite to the base of
the frond. A section made near the lower extremity of the stalk is nearly
semicircular, and discloses two roundish fibro-vascular bundles side by
side near the middle, and a minute thread of sclerenchyma, or hard dark
tissue, on the inner side of each bundle. A section just below the frond
shows the two fibro-vascular bundles united into one, and the angles of
the stalk slightly extended, forming very narrow wing-like borders. The
minute inner filaments of sclerenchyma are never continued far up the
stalk, and are sometimes wanting altogether.
The frond is from three to six inches long, and usually half an inch to
an inch broad at the base, from which the general outline tapers to a
long and slender point, not so long as the prolongation of the
walking-leaf, and very rarely, if ever, rooting at the apex.[4] The
fronds are mostly erect, sub-coriaceous or firmly membranaceous, smooth
above, but with a few minute setulose scales beneath, deeply pinnatifid
in the lower and middle portion, and sinuately lobed above, the long
terminal portion undulate on the margins. The midrib is broad and well
defined: it is winged throughout its length; the wing narrow at the base
of the frond, but constantly widening upwards.
The lobes are irregularly roundish-ovate, sinuate, crenate or slightly
toothed; the lowest ones occasionally drawn out into an acuminate point
an inch long. Most of the lobes are attached to the wing of the midrib by
a broad base: the lower ones sometimes have a short stalk.
The veins are everywhere free: in the lower lobes, if these are
acuminate, the veins are pinnately branched from a mid-vein; elsewhere
they are forked or dichotomous. The sori are mostly single, though here
and there one will be diplazioid,—most commonly the lowest one on the
superior side of the lobe. The indusia are very delicate; and the free
edge is directed toward the middle of the lobe, excepting the indusia of
the sori nearest the midrib, and these open toward the midrib. The sori
are usually very full of sporangia, and, when ripe, nearly cover the back
of the frond: even the narrow acumination bears a sorus at each
undulation of the margin. Spores ovoid-bean-shaped, with reticulating
ridges and an irregular winged border.
This is now admitted by all pteridologists to be a distinct species;
though it was formerly confounded with the _Camptosorus_, from which it
is clearly distinguished by the free veins, the mostly single indusia,
and the usual absence of a proliferous bud at the apex of the frond. Some
of the less compound and more attenuated forms of _A. montanum_ come much
nearer to it; but in its simplest form this other species always has the
fronds fairly pinnate, and its more compound forms resemble the _A.
pinnatifidum_ very little.
I take occasion to express my thanks to Hon. Thomas M. Peters of Moulton,
Alabama, who has sent me abundant and fine specimens of this fern and of
other rare species which are found in the northern part of Alabama.