EVERGREEN WOOD-FERN.
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.
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.