Kitabı oku: «Beautiful Ferns», sayfa 5

PELLÆA GRACILIS, Hooker.
Slender Cliff-Brake

Pellæa gracilis: – Root-stock slender, creeping, cord-like, scantily furnished with little ovate appressed scales; stalks scattered, slender, a span long or less, brownish-stramineous, somewhat shining, darker and slightly chaffy at the base; fronds two to four inches long, thin and tender, smooth, ovate or ovate-oblong, pinnate; pinnæ few, the lower two to four pairs once or twice pinnatifid, the uppermost simple; segments of the sterile fronds adnate-decurrent, roundish-obovate, crenately lobed and toothed; those of the taller fertile fronds lanceolate or linear-oblong, and more distinct, entire or auricled, terminal ones longest; veins rather distant, mostly once forked; involucre broad and continuous, delicately membranaceous.

Pellæa gracilis, Hooker, Sp. Fil., ii., p. 138, t. cxxxiii, B. – Eaton, in Gray’s Manual, ed. v., p. 659; Ferns of the South-West, p. 319. – Hooker & Baker, Syn. Fil., p. 145. – Porter & Coulter, Syn. Fl. Colorado, p. 153.

Pteris gracilis, Michaux, Fl. Bor. – Am., ii., p. 262. – Swartz, Syn. Fil., p. 99. – Willdenow, Sp. Pl., v., p. 376. – Pursh, Fl. Am. Sept., ii., p. 668. – Hooker, Fl. Bor. – Am., ii., p. 264.

Allosorus gracilis, Presl, Tent. Pterid., p. 153. – Torrey, Fl. New York, ii., p. 486. – Gray, Manual, ed. i., p. 624; ed. ii., p. 591, t. ix. – Parry, in Owen’s Geol. Surv. of Wisconsin, etc., p. 621. – Mettenius, Fil. Hort. Lips., p. 44.

Cheilanthes gracilis, Kaulfuss, Enum. Fil., p. 209.

Pteris Stelleri, Gmelin, “Nov. Com. Petrop., xii., p. 519, t. 12, f. 1.”

Allosorus Stelleri, Ruprecht, Distr. Crypt. Vasc. in Imp. Ross., p. 47. – Ledebour, Fl. Ross., iv., p. 526. – Moore, Ind. Fil., p. 46. – Lawson, in Canad. Naturalist, i., p. 272.

Allosorus minutus & Pteris minuta, Turczaninow, fide Moore.

Hab. – Crevices of damp and shaded calcareous rocks, especially in deep glens; Labrador, Butler, to British Columbia, and southward to Iowa, Parry, Wisconsin and Pennsylvania. Also in Colorado, near Breckinridge City, Brandegee. Siberia, Tibet and the Himalayas. It is found in Sunderland, Massachusetts; at Trenton Falls, Chittenango Falls, and other deep glens in Central New York; in Lycoming and Sullivan Counties, Pennsylvania, and in other similar places in Vermont, Michigan, etc., but is by no means a common plant.

Description: – This is the most delicate of all the Pellæas, and has fronds a good deal like those of Cryptogramme acrostichoides, but tenderer, and with sub-marginal fructification. The root-stock is very slender, scarcely more than half a line in thickness, and sometimes two or three inches long. It is so hidden in the crevices of the rocks that it is seldom secured by collectors. The scales are minute, appressed to the root-stock, and almost filmy in their delicacy.

The stalks are scattered along the root-stock, and are generally about five or six inches long, those of the fertile fronds longer, stouter and of a darker color than the others. They are smooth and somewhat polished, but lighter in color and far more tender in consistency than in most of our other species of this genus.

The fertile and the sterile fronds are unlike, though both are very delicately membranaceous, and pinnate with once or twice pinnatifid pinnæ. The rachis is not winged in its lower half, except in very small fronds, but above the middle it is narrowly winged, as are also its divisions. The lowest one or two pairs of pinnæ are twice pinnatifid in the largest specimens, but more commonly but once pinnatifid. In the sterile fronds the segments of the pinnæ are very plainly adnate to the secondary midrib, and are roundish or roundish-obovate in shape. They are from three to six lines long and about two-thirds as broad. Their margin is more or less lobed and crenately toothed. In the fertile fronds the segments are more distinct, longer and narrower, measuring often six to ten lines in length and one or two in width. The terminal pinna of the frond and the terminal segments of the pinnæ are considerably longer than the others. The veins are conspicuous, and distant, much more so than in our other species of Pellæa. They fork once about midway between the midvein and the margin, and sometimes, especially in fertile fronds, a second time just within the margin.

The involucre is continuous, broad, and even more delicate than the frond itself. The sporangia are comparatively scanty, and are fully covered by the involucre. The spores are spheroid-tetrahedral and obscurely trivittate.

Mr. Moore and some other authors are disposed to insist on the right of priority belonging to the specific name Stelleri. But the name gracilis has been used by nearly every writer on American Ferns since the time of Michaux, and will most probably be kept up rather than the other.

It should be noted that Ruprecht considered his Allosorus Stelleri to be distinct from our plant, and mentions several points of difference in his work on the Distribution of Vascular Cryptogamia in the Russian Empire.

The figure is taken from specimens collected in Sunderland, Hampshire County, Massachusetts, by the late Rev. David Peck.

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.

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.