Fronds upright, eight to eighteen inches high, linear-lanceolate, the fertile ones much taller, and pinnate. Pinnae scarcely an inch long, the lower ones very much shorter, alternate, spreading, finely serrate or incised, the base auricled. Sori numerous, rather near the midvein, stipe and rachis l.u.s.trous brown. ("Ebony.")

This rigidly upright but graceful fern flourishes in rocky, open woods, and on rich, moist banks, often in the neighborhood of red cedars. Having come upon it many times in our rambles, we should say it was not uncommon.

A lightly incised form of the pinnae has been described as var. _serratum_.

A handsome form discovered in Vermont in 1900 by Mrs. Horton and named _Hortonae_ (also called _incisum_) has plume-like fronds with the pinnae cut into oblique lobes, which are coa.r.s.ely serrate.

[Ill.u.s.tration: Ebony Spleenwort. _Asplenium platyneuron_ (Melrose, Ma.s.s., G.E. Davenport)]

[Ill.u.s.tration: Bradley's Spleenwort. _Asplenium Bradleyi_ a, from Maryland; b, from Kentucky (From Waters's "Ferns," Henry Holt & Co.)]

(7) BRADLEY'S SPLEENWORT. _Asplenium Bradleyi_

Fronds oblong-lanceolate, pinnate, three to ten inches long. Pinnae oblong-ovate, obtuse, incised or pinnatifid into oblong, toothed lobes.

The basal pinnae have broad bases, and blunt tips and are slightly stalked.

Stipes and rachis dark brown and the sori short, near the midrib.

A rare and beautiful fern growing on rocks preferring limestone and confined mostly to the southern states. Newburg, N.Y., to Kentucky and Alabama, westward to Arkansas.

(8) MOUNTAIN SPLEENWORT. _Asplenium montanum_

Fronds ovate-lanceolate from a broad base, two to eight inches long, somewhat leathery, pinnate. Pinnae ovate-oblong, the lowest pinnately cleft into oblong or ovate cut-toothed lobes, the upper ones less and less divided. Rachis green, broad, and flat.

[Ill.u.s.tration: Mountain Spleenwort (From the "Fern Bulletin")]

Small evergreen ferns of a bluish-green color, growing in the crevices of rocks and cliffs. Connecticut to Ohio, Kentucky, Arkansas and southwest.

July. Rare. Williams, in his "Ferns of Kentucky," says of this species, "Common on all sandstone cliffs and specimens are large on sheltered rocks by the banks of streams."

(9) RUE SPLEENWORT. _Asplenium Ruta-muraria_

Fronds evergreen, small, two to seven inches long, deltoid-ovate, two to three pinnate below, simply pinnate above, rather leathery in texture.

Divisions few, stalked, from cuneate to roundish-ovate, toothed or incised at the apex. Veins forking. Rachis and stipe green. Sori few, soon confluent.

[Ill.u.s.tration: The Rue Spleenwort. _A. Ruta-muraria_ (Top, Lake Huron--Lower Left, Mt. Toby, Ma.s.s.--Lower Right, Vermont) (From Herbarium of Geo. E. Davenport)]

This tiny fern grows from small fissures in the limestone cliffs, and is rather rare in this country; but in Great Britain it is very common, growing everywhere on walls and ruins. From Mt. Toby, Ma.s.s., and Willoughby Mountain, Vt., to Michigan, Missouri, Kentucky and southward.

B. THE LARGE SPLEENWORTS. _Athrium_

The following species, which are often two to three feet high and grow in rich soil, are quite different in appearance and habits from the small rock spleenworts just described. Some botanists have kept them in the genus _Asplenium_ because their sori are usually rather straight or only slightly curved, but others are inclined to follow the practice of the British botanists and put them into a separate group under _Athrium_. Nearly all agree that the lady fern, with its variously curved sori, should be placed here, and many others would place the silvery spleenwort in the same genus, partly because of its frequently doubled sori. In regard to the last member of the group, the narrow-leaved spleenwort, there is more doubt. The sori taken separately would place it with the _Aspleniums_, but considering its size, structure, habits of growth and all, it seems more closely allied to the two larger ferns than to the little rock species. We shall group the three together as the large spleenworts, or for the sake of being more definite adopt Clute's felicitous phrase.

THE LADY FERN AND ITS KIN

1. THE LADY FERNS

Fronds one to three feet high, broadly lanceolate, or ovate-oblong, tapering towards the apex, bipinnate. Pinnae lanceolate, numerous. Pinnules oblong-lanceolate, cut-toothed or incised. Fruit-dots short, variously curved. Indusium delicate, often reniform, or shaped like a horseshoe, in some forms confluent at maturity.

Widely distributed, common and varying greatly in outline. The newer nomenclature separates the lady fern of our section into two distinct species, which should be carefully studied.[A]

[Footnote A: See monograph by F.K. b.u.t.ters in _Rhodora_ of September, 1917.]

(1) THE UPLAND LADY FERN. ATHRIUM ANGuSTUM

_Asplenium Flix-femina_

The rootstock or rhizome of the Upland Lady Fern here pictured shows how the thick, fleshy bases of the old fronds conceal the rootstock itself. In the Lowland Lady Fern the rootstock is but slightly concealed by old stipe bases, and so may be distinguished from its sister fern.

One design of such rootstocks is to store up food (mostly starch), during the summer to nourish the young plants as they shoot forth the next spring.

The undecayed bases of the old stipes are also packed with starch for the same purpose.

[Ill.u.s.tration: Rootstock of the Upland Lady Fern]

[Ill.u.s.tration: The same split lengthwise (From Waters's "Ferns," Henry Holt & Co.)]

[Ill.u.s.tration: Sori of Lady Fern. _Athyrium angustum_]

Rootstocks horizontal, quite concealed by the thick, fleshy bases of old fronds. Scales of the long, tufted stipes dark brown. Indusium curved, often horseshoe-shaped, usually toothed or fringed with fine hairs, but without glands. Fronds bipinnate, one to three feet high, widest near the middle.

This is the common species of northern New England and the Canadian Provinces. The fronds differ very widely in form and a great many varieties have been pointed out, but the fern student, having first learned to identify the species, will gradually master the few leading varieties as he meets them.

Those growing in warm, sunny places where the fruit-dots when mature incline to cover the whole back of the frond are called "sun forms." These are varieties TPIc.u.m and ELaTIUS, both with the pinnae obliquely ascending (including variety _angustum_ of D.C. Eaton), but the latter has broader fronds with the pinnules of the sterile fronds oblong-lanceolate, somewhat acute and strongly toothed or pinnatifid.

[Ill.u.s.tration: Varieties of Lady Fern Left to right--1st and 2nd, Var.

_typic.u.m; 3d, elatius; 4th, rubellum; 5th, uncertain, perhaps confertum_]

Var. RUBeLLUM has the sori distinct even when mature; its pinnules stand at a wide angle from the rachis of the pinna and are strongly toothed or pinnatifid with obtuse teeth. This variety favors regions with cool summers, or dense shade in warmer regions. The term RUBeLLUM alludes to the reddish stems so often seen but this sign alone may not determine the variety. It occurs throughout the range of the species, being a common New England fern. Fernald remarks that this is also a common form of the species in southern Nova Scotia.

Among other varieties named by b.u.t.ters are CONFeRTUM, having the pinnules irregularly lobed and toothed; joined by a membranous wing, the lobes of the pinnules broad and overlapping, giving the fern a compact appearance; LACINIaTUM with pinnules very irregular in size and shape, with many long, acute teeth, which project in various directions. "An abnormal form which looks as if it had been nibbled when young."

These varieties are represented in the Gray Herbarium.

(2) THE LOWLAND LADY FERN

ATHRIUM ASPLENIIDES

Rootstocks creeping, not densely covered with the persistent bases of the fronds. Stipes about as long as the blade. Scales of the stipe very few, seldom persistent, rarely over 3-16 of an inch long. Fronds narrowly deltoid, lanceolate, widest near the base, the second pair of pinnae commonly longest. Indusia ciliate, the cilia (hairs) ending in glands.

Spores dark, netted or wrinkled.

[Ill.u.s.tration: Lowland Lady Fern. ATHYRIUM ASPLENIOIDES (From the Gray Herbarium)]

The following two forms are named by b.u.t.ters:

F. TPIc.u.m. The usual form frequent in eastern Ma.s.sachusetts, Rhode Island, Connecticut, New York, Pennsylvania, North Carolina, Ohio, and Missouri.

F. SUBTRIPINNaTUM. An unusually large and rare form with triangular, lanceolate, and pinnatifid pinnules, having blunt, oblong segments. Wet situations in half shade. Ma.s.sachusetts, West Virginia, and Virginia.