Beautiful Ferns

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.

ONOCLEA SENSIBILIS, Linnæus.

Sensitive Fern

Onoclea sensibilis: – Root-stock creeping, elongated; stalks scattered, nearly chaffless, a few inches to over a foot high; fronds dimorphous; sterile ones triangular-ovate, foliaceous, smooth, quickly withering when plucked, deeply pinnatifid into several oblong-lanceolate entire or sinuate or sinuately pinnatifid segments, the lowest pair sometimes distinct, the rest connected by a wing which widens upwards; the veins reticulated and forming narrow paracostal areoles, and, outside of these, copious oblong or hexagonal meshes; fertile fronds shorter, contracted, rigid, closely bipinnate; the pinnules rolled up into berry-like bodies; veins free, simple or forked, soriferous on the back; sporangia borne on an elevated receptacle, half surrounded by a very delicate somewhat hood-like indusium attached at the base of the receptacle.

Onoclea sensibilis, Linnæus, Sp. Pl., p. 1517. – Michaux, Fl. Bor. – Am., ii., p. 272. – Swartz, Syn. Fil., p. 110. – Schkuhr, Krypt. Gew., p. 95, t. 102. – Willdenow, Sp. Pl., v., p. 287. – Pursh, Fl. Am. Sept., ii., p. 665. – Hooker, Gen. Fil., t. lxxxii; Fl. Bor. – Am., ii., p. 262; Sp. Fil., iii., p. 160. – Torrey, Fl. New York, ii., p. 499. – Gray, Manual, ed. i., p. 457; ed. ii., p. 599, t. xii; ed. v., p. 668, t. xviii; Botany of Japan, in Mem. Amer. Acad. (n. s.) vi., p. 421. – Mettenius, Fil. Hort. Lips., p. 97. – Maximowicz, Prim. Fl. Amur., p. 337. – Eaton, in Chapman’s Flora, p. 596. – Hooker & Baker, Syn. Fil., p. 46. – Miquel, Prolus. Fl. Jap., in Ann. Mus. Bot. Lugd. – Batav., iii., p. 179. – Milde, Fil. Eur. et Atlant., p. 157. – Redfield, in Bulletin of Torrey Botan. Club, vi., p. 4. – Williamson, Ferns of Kentucky, p. 109, t. xli; Fern-Etchings, t. xlv.

Onoclea obtusilobata, Schkuhr, Krypt. Gew., p. 95, t. 103. – Pursh, Fl. Am. Sept., ii., p. 665.

Onoclea obtusiloba, Link, Fil. Hort. Lips., p. 37.

Osmunda frondibus pinnatis foliolis superioribus basi coadunatis, omnibus lanceolatis, pinnato-sinuatis, Linnæus, Hort. Cliff., p. 472. – Gronovius, Fl. Virginica, p. 196; ed. ii., p, 163. – (Other ancient names are repeated by Linnæus and Willdenow.)

Hab. – Wet meadows and thickets, from New Brunswick to the Saskatchewan, extending southward through Dacotah, Kansas, and Arkansas to Louisiana, and eastward to St. Augustine, Florida, one of our commonest and most abundant ferns, often occupying large portions of land to the partial exclusion of other plants. Not found in western America or in Europe, but occurring in Japan, Mantchooria and eastern Siberia.

Description: – The root-stock is about one-third of an inch thick, and irregularly roundish in section. It creeps widely below the surface of the ground, rooting freely and often forking, so that in cultivation it is very difficult to confine the plant to one spot. The root-stock contains six or eight roundish or flattened fibro-vascular bundles arranged in a circle near the outer surface. It bears no chaff. The stalks are scattered along its length, the apex being covered with the thickened stalk-bases of next year’s fronds, and the stalks for the present year rising a few inches back of the apex.

The fronds are truly dimorphous, the fertile ones being so unlike the sterile, that no one who is unacquainted with the plant would suppose they had anything to do with each other.

The sterile fronds vary in length from one or two inches to fifteen or eighteen, and are supported on stalks usually rather longer still, so that, while the smallest plants may be concealed in the grass, the tallest ones are often fully three feet high. The bases of the stalks are flattened, discolored and very sparingly chaffy; the upper part is green in the living plant, brownish-stramineous when dried, smooth and naked, rounded at the back, and slightly furrowed in front. It contains two obliquely-placed strap-shaped fibro-vascular bundles, which unite below the base of the frond and form one having a U-shaped section. The outline of the sterile fronds is triangular or triangular-ovate. The midrib is winged, either from the very base, or from the second pair of segments; the wing at its lower extremity very narrow, but gradually widening towards the apex, so that its greatest width is but little less than that of the terminal segment. The number of segments in the smallest fronds is two or three on each side; in the largest fronds twelve or thirteen on each side. The lowest segments are rather more than half as long as the whole frond; the next segments usually a little smaller, but sometimes a little longer than the first pair, and the remaining ones rapidly decreasing. The segments are broadly lanceolate or oblong-lanceolate, narrowed at the base, especially the lower ones, and either rounded or sub-acute at the apex. The sinuses between them are rounded, and are gradually narrowed towards the apex of the frond. The segments are very minutely serrulate on the edges; the smallest ones otherwise entire, and the larger ones either with sinuous margins or, in large fronds, deeply sinuous-pinnatifid. The texture is herbaceous, the surfaces perfectly smooth, the color of the upper surface grass-green, of the lower surface paler and slightly glaucescent. The fronds wilt very soon after plucking them, and in wilting there is a slight disposition to fold the segments together, face to face, for which reason the plant has received the name of “Sensitive-Fern.” The first frost of autumn destroys the sterile fronds; and a late frost in May or June does the same. The midribs are prominent, and the veins conspicuous; the latter being copiously reticulated into areoles which enclose no free veinlets. Along the sides of the midribs and midveins are very long and narrow areoles, and outside of these are obliquely-placed oblong areoles in several irregular rows.

The fertile fronds are not very common, and a young botanist may search in vain for them for a long time. They stand only about half as high as the sterile fronds, and are very rigid. They are nearly black in color: in winter they dry up, but remain erect through the next summer, so that a fruiting plant often has fertile fronds standing of two years’ growth. The frond is only a few (usually four to six) inches long, and consists of from four to ten pairs of appressed fleshy or cartilaginous pinnæ, which are divided into a double row of sub-globose bead-like segments or pinnules; the whole looking like a small and narrow but dense cluster of diminutive grapes. Each pinnule has its edges so much recurved that the whole forms a sort of pouch, apparently filled with sporangia.

Mr. Faxon has made a careful study of the sori, and has very kindly furnished the account given below.5

The articulations of the sporangia are said by Fée to be twenty-eight to thirty-two, and more numerous than in any other fern. I have counted only thirty at most, and more frequently only twenty-eight. The spores are ovoid and very dark-colored.

Var. obtusilobata, Torrey, Fl. New York, ii., p. 499, t. clx (Onoclea obtusilobata, Schkuhr), is not a permanent variation of the species, but is based on a not infrequent condition of the plant, in which the pinnæ of some of the foliaceous fronds become deeply pinnatifid into obovate segments, which have mostly free veins and imperfectly developed sori. The indusia appear as little whitish scales on the back of the veins. It occurs in almost all places where the plant is common, is often produced from root-stocks which bear also normal fronds, and presents all gradations from the usual sterile frond to the proper fertile one. Ragiopteris onocleoides of Presl is founded on a young fertile frond of this species placed with a sterile one of what Milde judges to be a monstrous form of Aspidium Filix-mas. Maximowicz describes a var. interrupta, from the Amoor region, in which the fertile frond nearly equals the sterile, and has elongated pinnæ, with remote segments. This condition is also sometimes seen in American specimens, and is hardly a true variety.

In an article on “The late Extinct Floras of North America,” which appeared in Vol. ix of the Annals of the New York Lyceum of Natural History, in April, 1868, Professor Newberry describes certain fossil specimens of ferns occurring in Miocene argillaceous limestone at Fort Union, Dacotah, and refers them with little hesitation to this species. I have not seen the specimens, but, as similar venation and not very dissimilar fronds are seen in Woodwardia and Pteris, one may perhaps doubt the absolute certainty of the identification.

1

Milde indicates several other unimportant variations; and Hooker & Baker have as varieties of this species the East Indian Aspidium cochleatum, and Aspidium elongatum, from Madeira and the Canary Islands. The latter they give as occurring also in the southern United States, evidently supposing it to be the long-lost A. Ludovicianum of Kunze. For abundant synonymy of Aspidium Filix-mas the student is referred especially to the works of Hooker, Milde, Mettenius and Moore, as quoted above.

2

See the “Flora of New York” for some figures of laciniated and forking fronds.

3

Prof. Amos Eaton, grandfather of the present writer. Eaton’s “Manual of Botany” went through eight editions from 1817 to 1841.

4

I find one or two instances of a slight enlargement of the apex, as if there were an attempt to form a proliferous bud.

5

“In O. sensibilis the sori are borne on the middle of the vein, and consist of a tough cylindrical receptacle, three or four diameters in height, bearing sporangia thickly all over its surface, and covered when young by a delicate hood-like indusium, attached half-way or more around the base of the receptacle on the inferior side, and having the crenulate-margined opening toward the apex of the segment. At an early stage the blackberry-shaped sorus is almost entirely covered by the indusium, which resembles a closely drawn cowl, but with the growth of the sporangia it is thrown back, or rent, and soon disappears, the sori becoming confluent. The receptacle is very persistent, and may be seen, covered with the stalks of the sporangia, in the dried last-year’s fertile fronds, which are always found where the plant grows.”