To me the greatest charm the ferns possess is that of their surroundings. No other plants know so well how to choose their haunts. If you wish to know the ferns you must follow them to Nature's most sacred retreats. In remote, tangled swamps, overhanging the swift, noiseless brook in the heart of the forest, close to the rush of the foaming waterfall, in the depths of some dark ravine, or perhaps high up on mountain-ledges, where the air is purer and the world wider and life more beautiful than we had fancied, these wild, graceful things are most at home.
You will never learn to know the ferns if you expect to make their acquaintance from a carriage, along the highway, or in the interval between two meals. For their sakes you must renounce indolent habits. You must be willing to tramp tirelessly through woods and across fields, to climb mountains and to scramble down gorges. You must be content with what luncheon you can carry in your pocket. And let me tell you this. When at last you fling yourself upon some bed of springing moss, and add to your sandwich cresses fresh and dripping from the neighboring brook, you will eat your simple meal with a relish that never attends the most elaborate luncheon within four walls. And when later you surrender yourself to the delicious sense of fatigue and drowsy relaxation which steals over you, mind and body, listening half-unconsciously to the plaintive, long-drawn notes of the wood-birds and the sharp "tsing" of the locusts, breathing the mingled fragrance of the mint at your feet and the pines and hemlocks overhead, you will wonder vaguely why on summer days you ever drive along the dusty high-road or eat indoors or do any of the flavorless conventional things that consume so large a portion of our lives.
Of course what is true of other out-door studies is true of the study of ferns. Constantly your curiosity is aroused by some bird-note, some tree, some gorgeously colored butterfly, and, in the case of ferns especially, by some outcropping rock, which make you eager to follow up other branches of nature-study, and to know by name each tree and bird and butterfly and rock you meet.
The immediate result of these long happy days is that "golden doze of mind which follows upon much exercise in the open air," the "ecstatic stupor" which Stevenson supposes to be the nearly chronic condition of "open-air laborers." Surely there is no such preventive of insomnia, no such cure for nervousness or morbid introspection as an absorbing out-door interest. Body and mind alike are invigorated to a degree that cannot be appreciated by one who has not experienced the life-giving power of some such close and loving contact with nature.
WHEN AND WHERE TO FIND FERNS
"It is no use to direct our steps to the woods if they do not carry us thither. I am alarmed when it happens that I have walked a mile into the woods bodily, without getting there in spirit."—Thoreau
WHEN AND WHERE TO FIND FERNS
It is in early spring that one likes to take up for the first time an out-door study. But if you begin your search for ferns in March, when the woods are yielding a few timid blossoms, and the air, still pungent with a suggestion of winter, vibrates to the lisping notes of newly arrived birds, you will hardly be rewarded by finding any but the evergreen species, and even these are not likely to be especially conspicuous at this season.
Usually it is the latter part of April before the pioneers among the ferns, the great Osmundas, push up the big, woolly croziers, or fiddleheads, which will soon develop into the most luxuriant and tropical-looking plants of our low wet woods and roadsides.
At about the same time, down among last year's Christmas Ferns, you find the rolled-up fronds of this year, covered with brown or whitish scales. And now every day for many weeks will appear fresh batches of young ferns. Someone has said that there is nothing more aggressively new-born than a young fern, and this thought will recur constantly as you chance upon the little wrinkled crozier-like fronds, whether they are bundled up in wrappings of soft wool or protected by a garment of overlapping scales, or whether, like many of the later arrivals, they come into the world as naked and puny as a human baby.
Once uncurled, the ferns lose quickly this look of infancy, and embody, quite as effectively, even the hardiest and coarsest among them, the slender grace of youth. Early in May we find the Osmundas in this stage of their development. The Royal Fern, smooth and delicate, is now flushing the wet meadows with its tender red. In the open woods and along the roadside the Interrupted and the Cinnamon Ferns wear a green equally delicate. These three plants soon reach maturity and are conspicuous by reason of their unusual size and their flower-like fruit-clusters.
On the rocky banks of the brook, or perhaps among the spreading roots of some forest-tree, the Fragile Bladder Fern unrolls its tremulous little fronds, on which the fruit-dots soon appear. Where there is less moisture and more exposure we may find the Rusty Woodsia, now belying its name by its silvery aspect. At this same season in the bogs and thickets we should look for the curious little Adder's Tongue.
By the first of June many of the ferns are well advanced. On the hill-sides and along the wood-path the Brake spreads its single umbrella-like frond, now pale green and delicate, quite unlike the umbrageous-looking plant of a month later. Withdrawing into the recesses formed by the pasture-rails the Lady Fern is in its first freshness, without any sign of the disfigurements it develops so often by the close of the summer. Great patches of yellowish green in the wet meadows draw attention to the Sensitive Fern, which only at this season seems to have any claim to its title. The Virginia Chain Fern is another plant to be looked for in the wet June meadows. It is one of the few ferns which grows occasionally in deep water.
The Maidenhair, though immature, is lovely in its fragility. Thoreau met with it on June 13th and describes it in his diary for that day: "The delicate maiden-hair fern forms a cup or dish, very delicate and graceful. Beautiful, too, its glossy black stem and its wave-edged, fruited leaflets."
In the crevices of lofty cliffs the Mountain Spleenwort approaches maturity. And now we should search the moist, mossy crannies of the rocks for the Slender Cliff Brake, for in some localities this plant disappears early in the summer.
We may hope to find most of the ferns in full foliage, if not in fruit, by the middle of July. Dark green, tall and vigorous stand the Brakes. The Crested Shield Fern is fruiting in the swamps, and in the deeper woods Clinton's and Goldie's Ferns are in full fruitage. Magnificent vase-like clusters of the Ostrich Fern spread above our heads in the thicket along the river-shore. The Spinulose Shield Fern and the Evergreen Wood Fern meet us at every turn of the shaded path beside the brook, and on the rocky wooded hill-side the Christmas Fern is almost as abundant. Where the stream plunges from above, the Bulblet Bladder Fern drapes the steep banks with its long feathery fronds. In the wet meadows and thickets the New York Fern and the Marsh Shield Fern are noticeable on account of their light green color and delicate texture. On mountain-ledges we look for the little Woodsias, and in rocky places, often in the shadow of red cedars, for the slim erect fronds of the Ebony Spleenwort.
Possibly it will be our good fortune to discover the blue-green foliage of the Purple Cliff Brake springing from the crevices of some dry limestone cliff. Almost surely, if we search the moist, shaded rocks and ravines in the neighborhood, we shall greet with unfailing pleasure the lovely little Maidenhair Spleenwort.
In somewhat southern localities the tapering, yellow-green fronds of the Dicksonia or Hay-scented Fern are even more abundant and conspicuous than the darker foliage of the Spinulose Shield Fern. They abound along the roadsides and in partially shaded or open pastures, the spores ripening not earlier than August.
In the same month we find in full maturity three interesting wood ferns, all belonging to the same group. The first of these is the Long Beech Fern. It is abundant in many of our northern woods and on the rocky banks of streams. Its shape is noticeably triangular, the triangle being longer than broad. Its texture is rather soft and downy. The lowest pair of pinnæ stand forward and are conspicuously deflexed, giving an easy clew to the plant's identity.
The most attractive member of the group to my mind is the Oak Fern. I find it growing abundantly in the cedar swamps and wet woods of somewhat northern localities. Its delicate, spreading, three-branched frond suggests that of a young Brake. This plant is peculiarly dainty in the early summer, as frequently later in the year it becomes blotched and disfigured.
The Broad Beech Fern seeks drier neighborhoods, and often a more southern locality than its two kinsmen. Its triangular fronds, broader than they are long, are conspicuous on account of the unusual size of the lowest pair of pinnæ.
A common plant in the rich August woods is the Virginia Grape Fern, with its spreading leaf and branching fruit-cluster. The rather coarsely cut fronds of the Silvery Spleenwort are also frequently met with in the same neighborhood. Occasionally in their companionship we find the delicate and attractive Narrow-leaved Spleenwort.
August is the month that should be chosen for expeditions in search of some of our rarest ferns. In certain wild ravines of Central New York, at the foot of shaded limestone cliffs, the glossy leaves of the Hart's Tongue are actually weighed down by the brown, velvety rows of sporangia which emboss their lower surfaces. Over the rocks near-by, the quaint, though less unusual, Walking Leaf runs riot. Perhaps in the crevices of the overhanging cliff the little Rue Spleenwort has secured a foothold for its tiny fronds, their backs nearly covered with confluent fruit-dots.
On the mountain-ledges of Northern New England we should look for the Green Spleenwort, and for the Fragrant Shield Fern. Along rocky mountain-streams Braun's Holly Fern may be found. In wet woods, usually near the coast, the Net-veined Chain Fern is occasionally conspicuous.
More southern localities must be visited if we wish to see in its home the Hairy Lip Fern, whose most northern stations were on the Hudson River (for I do not know if this plant can be found there at present), and such rare Spleenworts as the Pinnatifid, Scott's and Bradley's.
In September the fruit-clusters of the little Curly Grass ripen in the low pine barrens of New Jersey. Over moist thickets, in rarely favored retreats from Massachusetts southward, clamber the slender strands of the Climbing Fern. Thoreau's diary of September 26th evidently refers to this plant: "The tree-fern is in fruit now, with its delicate, tendril-like fruit, climbing three or four feet over the asters, golden-rod, etc., on the edge of the swamp."
In moist places now we find the triangular much dissected leaf and branching fruit-cluster of the Ternate Grape Fern.
When October sets in, many of the ferns take their color-note from the surroundings. Vying with the maples along the roadside the Osmundas wear deep orange. Many of the fronds of the Dicksonia are bleached almost white, while others look fresh and green despite their delicate texture. On October 4th Thoreau writes of this plant:
"How interesting now, by wall-sides and on open springy hill-sides, the large straggling tufts of the Dicksonia fern above the leaf-strewn green sward, the cold, fall-green sward! They are unusually preserved about the Corner Spring, considering the earliness of this year. Long, handsome, lanceolate green fronds pointing in every direction, recurved and full of fruit, intermixed with yellowish and sere brown and shrivelled ones, the whole clump perchance strewn with fallen and withered maple leaves, and overtopped by now withered and unnoticed osmundas. Their lingering greenness is so much the more noticeable now that the leaves generally have changed. They affect us as if they were evergreen, such persistent life and greenness in the midst of decay. No matter how much they are strewn with withered leaves, moist and green they spire above them, not fearing the frosts, fragile as they are. Their greenness is so much the more interesting, because so many have already fallen, and we know that the first severe frost will cut off them too. In the summer greenness is cheap, now it is a thing comparatively rare, and is the emblem of life to us."
Oddly enough, with the first approach of winter the vigorous-looking Brake turns brown and quickly withers, usually without passing through any intermediate gradations of yellow.
In November we notice chiefly the evergreen ferns. The great round fruit-dots of the Polypody show distinctly through the fronds as they stand erect in the sunlight. A sober green, looking as though it were warranted fast, is the winter dress of the Evergreen Wood Fern. The Christmas Fern, bright and glossy, reminds one that the holiday season is not distant. These three plants are especially conspicuous in our late autumn woods. Their brave and cheerful endurance is always a delight. Later in the season the curled pinnæ of the Polypody seem to be making the best of cold weather. The fronds of the Christmas Fern and the Evergreen Wood Fern, still fresh and green, lie prostrate on the ground, their weakened stems apparently unable to support them erect, but undoubtedly in this position they are the better protected from the storm and stress of winter.
Many other ferns are more or less evergreen, but perhaps none are so important to our fall rambles as this sturdy group. Several of the Rock Spleenworts are evergreen, but their ordinarily diminutive stature dwindles with the increasing cold, and we seldom encounter them on our winter walks. The sterile fronds of a number of the Shield Ferns endure till spring. The Purple Cliff Brake and the Walking Leaf are also proof against ice and snow. Even in the middle of January the keen-eyed fern hunter may hope to make some discovery of interest regarding the haunts and habits of his favorites.
EXPLANATION OF TERMS
A fern is a flowerless plant growing from a rootstock (a), with leaves or fronds usually raised on a stalk, rolled up (b) in the bud,[A] and bearing on their lower surfaces (c) the spores, by means of which the plant reproduces.
A rootstock is an underground, rooting stem. Ferns are propagated by the growth and budding of the rootstock as well as by the ordinary method of reproduction. The fronds spring from the rootstock in the manner peculiar to the species to which they belong. The Osmundas, the Evergreen Wood Fern, and others grow in a crown or circle, the younger fronds always inside. The Mountain Spleenwort is one of a class which has irregularly clustered fronds. The fronds of the Brake are more or less solitary, rising from distinct and somewhat distant portions of the rootstock. The Botrychiums usually give birth to a single frond each season, the base of the stalk containing the bud for the succeeding year.
A frond is simple when it consists of an undivided leaf such as that of the Hart's Tongue or of the Walking Leaf (Fig. 1).
A frond is pinnatifid when cut so as to form lobes extending half-way or more to the midvein (Fig. 2).
A frond is once-pinnate when the incisions extend to the midvein (Fig. 3). Under these conditions the midvein is called the rachis (a), and the divisions are called the pinnæ (b).
A frond is twice-pinnate when the pinnæ are cut into divisions which extend to their midveins (Fig. 4). These divisions of the pinnæ are called pinnules (a).
A frond that is only once-pinnate may seem at first glance twice-pinnate, as its pinnæ may be so deeply lobed or pinnatifid as to require a close examination to convince us that the lobes come short of the midvein of the pinnæ. In a popular hand-book it is not thought necessary to explain further modifications.
The veins of a fern are free when, branching from the midvein, they do not unite with other veins (Fig. 5).
Ferns produce spores (Fig. 6) instead of seeds. These spores are collected in spore-cases or sporangia (Fig. 7). Usually the sporangia are clustered in dots or lines on the back of a frond or along its margins. These patches of sporangia are called sori or fruit-dots. They take various shapes in the different species. They may be round or linear or oblong or kidney-shaped or curved. At times they are naked, but more frequently they are covered by a minute outgrowth of the frond or by its reflexed margin. This covering is called the indusium. In systematic botanies the indusia play an important part in determining genera. But as often they are so minute as to be almost invisible to the naked eye, and, as frequently they wither away early in the season, I place little dependence upon them as a means of popular identification.
A fertile frond is one which bears spores.
A sterile frond is one without spores.
FOOTNOTE:
[A] Ophioglossum and the Botrychiums, not being true ferns, are exceptions.
FERTILIZATION, DEVELOPMENT, AND FRUCTIFICATION OF FERNS
Until very recently the development of ferns, their methods of fertilization and fructification have been shrouded in mystery. At one period it was believed that "fern-seed," as the fern-spores were called, possessed various miraculous powers. These were touched upon frequently by the early poets. In Shakespeare's "Henry IV" Gadshill exclaims:
"We have the receipt of fern-seed, we walk invisible."
He is met with the rejoinder:
"Nay, I think rather you are more beholden to the night than to fern-seed, for your walking invisible."
One of Ben Jonson's characters expresses the same idea in much the same words:
No fern-seed in my pocket."
In Butler's "Hudibras" reference is made to the anxieties we needlessly create for ourselves:
Equivocally without seed,
And have no possible foundation
But merely in th' imagination."
In view of the fact that many ferns bear their spores or "fern-seed" somewhat conspicuously on the lower surfaces of their fronds, it seems probable that the "fern" of early writers was our common Brake, the fructification of which is more than usually obscure, its sporangia or "fern-seed" being concealed till full maturity by the reflexed margin of its frond. This plant is, perhaps, the most abundant and conspicuous of English ferns. Miss Pratt believes it to be the "fearn" of the Anglo-Saxons, and says that to its profusion in their neighborhood many towns and hamlets, such as Fearnborough or Farnborough, Farningham, Farnhow, and others owe their titles. The plant is a noticeable and common one also on the Continent.
In 1848 the development of the fern was first satisfactorily explained. It was then shown that these plants pass through what has been called, not altogether happily the modern botanist thinks, an "alternation of generations." One "generation," the "sexual," consists of a tiny, green, plate-like object, termed the prothallium (Fig. 8). This is connected with the soil by hair-like roots. On its lower surface are borne usually both the reproductive organs of the fern, the antheridia, corresponding to the stamens or fertilizing organs of the flower, and the archegonia, performing the office of the flower's pistils, inasmuch as their germ-cells receive the fertilizing substance produced by the antheridia. But no seeds are formed as the result of this fertilization. Instead of this seed-formation which we note in the flowering plant, the germ-cell in the fern develops into a fern-plant, which forms the "asexual" generation.
First fronds of Maidenhair
The first fronds of this little plant are very small and simple, quite unlike the later ones. For a time the plant is nourished by the prothallium, but as soon as it is sufficiently developed and vigorous enough to shift for itself, the prothallium dies away, and the fern maintains an independent existence. Eventually it produces fronds which bear on their lower surfaces the sporangia containing the minute spores from which spring the prothallia.
For our present purpose it is enough to say that spores differ from seeds in that they are not the immediate result of the interaction of reproductive organs. They resemble seeds in that they are expelled from the parent-plant on attaining maturity, and germinate on contact with the moist earth.
Thus it is seen that the life-cycle of a fern consists of two stages:
First, the prothallium, bearing the reproductive organs; second, the fern-plant proper, developing the spores which produce the prothallium.
Along the moist, shaded banks of the wood road, or on decaying stumps, keen eyes will discern frequently the tiny green prothallia, although they are somewhat difficult to find except in the green-house where one can see them in abundance either in the boxes used for growing the young plants, or on the moist surfaces of flower-pots, where the spores have fallen accidentally and have germinated.
As the fertilization of the germ-cell in the archegonium cannot take place except under water, perhaps the fact is accounted for that ferns are found chiefly in moist places. This water may be only a sufficient amount of rain or dew to permit the antherozoids or fertilizing cells of the antheridium to swim to the archegonium, which they enter for the purpose of fertilizing the germ-cell.
It is interesting to examine with a good magnifying glass the sporangia borne on the lower surface of a mature fertile frond. In many species each sporangium or spore-case is surrounded with an elastic ring, which at maturity contracts so suddenly as to rupture the spore-case, and cause the expulsion of the numberless spores (Fig. 7).
NOTABLE FERN FAMILIES
OSMUNDA (Flowering Ferns)
Tall swamp ferns, growing in large crowns, with the fertile fronds or portions conspicuously unlike the sterile; sporangia opening by a longitudinal cleft into two valves.
ONOCLEA
Coarse ferns, with the fertile fronds rolled up into necklace-like or berry-like segments, and entirely unlike the broad, pinnatifid sterile ones. Fertile fronds unrolling at maturity, allowing the spores to escape, and remaining long after the sterile fronds have perished; sporangia stalked, ringed, bursting transversely.
WOODSIA
Small or medium-sized ferns, growing among rocks, with 1-2 pinnate or pinnatifid fronds and round fruit-dots; indusium thin and often evanescent, attached by its base under the sporangia, either small and open, or else early bursting at the top into irregular pieces or lobes; sporangia stalked, ringed, bursting transversely.
CYSTOPTERIS (Bladder Ferns)
Delicate rock or wood ferns, with 2-3 pinnate fronds and round fruit-dots; indusium hood-like, attached by a broad base to the inner side, soon thrown back or withering away; sporangia as above.
ASPIDIUM (Shield Ferns)
Ferns with 1-3 pinnate fronds and round fruit-dots; indusium more or less flat, fixed by its depressed centre; sporangia as above.
PHEGOPTERIS (Beech Ferns)
Medium-sized or small ferns, with 2-3 pinnatifid or ternate leaves, and small, round, uncovered fruit-dots; sporangia as above.
WOODWARDIA (Chain Ferns)
Large and rather coarse ferns of swamps or wet woods, fronds pinnate or nearly twice-pinnate; fruit-dots oblong or linear, sunk in cavities of the leaf and arranged in chain-like rows; indusium lid-like, somewhat leathery, fixed by its outer margin to a veinlet; veins more or less reticulated; sporangia as above.
ASPLENIUM (Spleenworts)
Large or small ferns, with varying fronds and linear or oblong fruit-dots; indusium straight or curved; sporangia as above.
PELLÆA (Cliff Brakes)
Small or medium-sized rock ferns, with pinnate fronds and sporangia borne beneath the reflexed margins of the pinnæ; sporangia as above.
BOTRYCHIUM (Moonworts)
(Belonging to the Fern Allies)
Fleshy plants, with fronds (usually solitary) divided into a sterile and a fertile portion, the bud for the succeeding year embedded in the base of the stem.
HOW TO USE THE BOOK
Before attempting to identify the ferns by means of the following Guide it would be well to turn to the Explanation of Terms, and with as many species as you can conveniently collect, on the table before you, to master the few necessary technical terms, that you may be able to distinguish a frond that is pinnatifid from one that is pinnate, a pinna from a pinnule, a fertile from a sterile frond.
You should bear in mind that in some species the fertile fronds are so unleaf-like in appearance that to the uninitiated they do not suggest fronds at all. The fertile fronds of the Onocleas, for example, are so contracted as to conceal any resemblance to the sterile ones. They appear to be mere clusters of fruit. The fertile fronds of the Cinnamon Fern are equally unleaf-like, as are the fertile portions of the other Osmundas and of several other species.
In your rambles through the fields and woods your eyes will soon learn to detect hitherto unnoticed species. In gathering specimens you will take heed to break off the fern as near the ground as possible, and you will not be satisfied till you have secured both a fertile and a sterile frond. In carrying them home you will remember the necessity of keeping together the fronds which belong to the same plant.
When sorting your finds you will group them according to the Guide. The broad-leaved Sensitive Fern, with its separate, dark-green fruit cluster, makes its way necessarily to Group I. To Group II goes your pale-fronded Royal Fern, tipped with brown sporangia. As a matter of course you lay in Group III the leaf-like but dissimilar sterile and fertile fronds of the Slender Cliff Brake. The spreading Brake, its reflexed margin covering the sporangia, identifies itself with Group IV. The oblong fruit-dots of the little Mountain Spleenwort carry it to Group V, while the round ones, like pin-heads, of the Evergreen Wood Fern announce it a member of Group VI.
The different ferns sorted, it will be a simple matter to run quickly through the brief descriptions under the different Groups till you are referred to the descriptions in the body of the book of the species under investigation.
GUIDE
For the purpose of identification the ferns described are arranged in six groups, according to their manner of fruiting.
GROUP I
STERILE AND FERTILE FRONDS TOTALLY UNLIKE; FERTILE FRONDS NOT
LEAF-LIKE IN APPEARANCE
1. SENSITIVE FERN
Onoclea sensibilis
Sterile fronds usually large; broadly triangular, deeply pinnatifid. Fertile fronds much contracted, with berry-like pinnules. In wet meadows. P. 54.
2. OSTRICH FERN
Onoclea Struthiopteris
Large. Sterile fronds once-pinnate, pinnæ pinnatifid. Fertile fronds contracted, with necklace-like pinnæ. Along streams and in moist woods. P. 56.
3. CINNAMON FERN
Osmunda cinnamomea
Large. Sterile fronds once-pinnate, pinnæ pinnatifid. Fertile fronds composed of cinnamon-brown fruit-clusters. In wet places. P. 60.
4. CURLY GRASS
Schizæa pusilla
Very small. Sterile fronds linear, grass-like. Fertile fronds taller, with a terminal fruit-cluster. In pine barrens of New Jersey. P. 63.
GROUP II
FERTILE FRONDS PARTIALLY LEAF-LIKE, THE FERTILE PORTION UNLIKE THE
REST OF THE FROND
[The species coming under the genera Botrychium and Ophioglossum may appear to belong to Group I, as the fertile and the sterile portions of their fronds may seem to the uninitiated like separate fronds, but in reality they belong to the one frond.]
5. ROYAL FERN
Osmunda regalis
Large. Sterile fronds twice-pinnate, pinnules oblong. Fertile fronds leaf-like below, sporangia in clusters at their summits. In wet places. P. 67.
6. INTERRUPTED FERN
Osmunda Claytoniana
Large. Sterile fronds once-pinnate, pinnæ pinnatifid. Fertile fronds leaf-like above and below, contracted in the middle with brown fruit-clusters. In wet places. P. 72.
7. CLIMBING FERN
Lygodium palmatum
Climbing, with lobed, palmate pinnæ and terminal fruit-clusters. Moist thickets and open woods. Rare. P. 75.
8. ADDER'S TONGUE
Ophioglossum vulgatum
Small. Sterile portion an ovate leaf. Fertile portion a slender spike. In moist meadows. P. 77.
9. RATTLESNAKE FERN
Botrychium Virginianum
Rather large. Sterile portion a thin, spreading, ternately divided leaf with three primary divisions; 1-2 pinnate. Fertile portion a branching fruit-cluster. In rich woods. P. 80.
10. TERNATE GRAPE FERN
Botrychium ternatum or dissectum
Of varying size, very fleshy. Sterile portion a broadly triangular, ternate, finely dissected leaf, long-stalked from near the base of the stem. Fertile portion a branching fruit-cluster. In moist meadows. P. 81.
11. LITTLE GRAPE FERN
Botrychium simplex
A very small fleshy plant. Sterile portion an oblong leaf more or less lobed. Fertile portion a simple or slightly branching spike. In moist woods and in fields. P. 82.
12. MOONWORT
Botrychium Lunaria
Usually small, very fleshy. Sterile portion divided into several fan-shaped lobes. Fertile portion a branching fruit-cluster. Mostly in fields. P. 84.
13. MATRICARY GRAPE FERN
Botrychium matricariæfolium
Small, more or less fleshy. Sterile portion ovate or oblong, once or twice pinnatifid. Fertile portion a branching fruit-cluster. In grassy woods and wet meadows. P. 86.
14. LANCE-LEAVED GRAPE FERN
Botrychium lanceolatum
Small, scarcely fleshy. Sterile portion triangular, twice-pinnatifid. Fertile portion a branching fruit-cluster. In woods and meadows. P. 86.
GROUP III
FERTILE FRONDS UNIFORMLY SOMEWHAT LEAF-LIKE IN APPEARANCE, YET
DIFFERING NOTICEABLY FROM STERILE FRONDS
15. SLENDER CLIFF BRAKE
Pellæa gracilis
A small fern, 1-3 pinnate. Very delicate. Fertile fronds taller, more contracted and simpler than the sterile, sporangia bordering the pinnæ. Usually on sheltered rocks, preferring limestone. P. 87.
16. PURPLE CLIFF BRAKE
Pellæa atropurpurea
Medium sized, 1-2 pinnate, leathery. Fertile fronds taller and more contracted than the sterile, sporangia bordering the pinnæ. Usually on exposed rocks, preferring limestone. P. 90.
17. CHRISTMAS FERN
Aspidium acrostichoides
Rather large, smooth and glossy, once-pinnate. Fertile fronds contracted at the summit where the fruit appears. In rocky woods. P. 96.
18. NARROW-LEAVED SPLEENWORT
Asplenium angustifolium
Tall and delicate, once-pinnate. Fertile fronds taller and narrower than the sterile. In moist woods in late summer. P. 98.
19. NET-VEINED CHAIN FERN
Woodwardia angustifolia
Large, fronds deeply pinnatifid, the fertile taller and more contracted than the sterile. In wet woods near the coast. P. 102.
GROUP IV
FERTILE AND STERILE FRONDS LEAF-LIKE AND SIMILAR; SPORANGIA ON OR
BENEATH A REFLEXED PORTION OF THE MARGIN
[The first clause bars out P. gracilis and P. atropurpurea, which otherwise would belong to Group IV as well as to Group III.]
20. BRAKE
Pteris aquilina
Large and coarse, frond 3-branched, spreading, each branch 2-pinnate, sporangia in a continuous line beneath the reflexed margin of the frond. In dry, somewhat open places. P. 105.
21. MAIDENHAIR
Adiantum pedatum
Graceful and delicate, frond forked at the summit of the stem, 2-pinnate, the pinnæ springing from the upper sides of the branches, pinnules one-sided, their upper margins lobed, bearing on their undersides the short fruit-dots. In rich woods. P. 108.
22. HAIRY LIP FERN
Cheilanthes vestita
Rather small, fronds 2-pinnate, hairy, fruit-dots "covered by the infolded ends of the rounded or oblong lobes." On rocks. P. 112.
23. HAY-SCENTED FERN
Dicksonia pilosiuscula
Rather large, pale, delicate and sweet-scented, fronds usually 2-pinnate, fruit-dots small, each on a recurved toothlet of the pinnule, borne on an elevated, globular receptacle. In moist thickets and in upland pastures. P. 114.
GROUP V
FERTILE AND STERILE FRONDS LEAF-LIKE AND SIMILAR; SPORANGIA IN LINEAR
OR OBLONG FRUIT-DOTS
24. LADY FERN
Asplenium Filix-fœmina
Rather large, fronds 2-pinnate, fruit-dots curved, often horseshoe shaped, finally confluent. In moist woods and along roadsides. P. 120.
25. SILVERY SPLEENWORT
Asplenium thelypteroides
Large, fronds once-pinnate, pinnæ deeply pinnatifid, lobes oblong and obtuse, fruit-dots oblong, silvery when young. In rich woods. P. 124.
26. RUE SPLEENWORT
Asplenium Ruta-muraria
Very small, fronds loosely 2-3 pinnate at base, pinnatifid above, fruit-dots linear-oblong, confluent when mature. On limestone cliffs. Rare. P. 126.
27. MOUNTAIN SPLEENWORT
Asplenium montanum
Small, fronds 1-2 pinnate, fruit-dots linear-oblong, often confluent. On rocks. P. 130.
28. EBONY SPLEENWORT
Asplenium ebeneum
Fronds slender and erect, once-pinnate, pinnæ eared on the upper or on both sides, stalk and rachis blackish and shining, fruit-dots oblong. On rocks and hill-sides. P. 134.
29. MAIDENHAIR SPLEENWORT
Asplenium Trichomanes
Small, fronds once-pinnate, pinnæ roundish, stalk and rachis purplish-brown and shining, fruit-dots short. In crevices of rocks. P. 136.
30. GREEN SPLEENWORT
Asplenium viride
Small, fronds linear, once-pinnate, brownish stalk passing into a green rachis. On shaded cliffs northward. P. 138.
31. SCOTT'S SPLEENWORT
Asplenium ebenoides
Small, fronds pinnate below, pinnatifid above, apex slender and prolonged, stalk and rachis blackish, fruit-dots straight or slightly curved. On limestone. Very rare. P. 140.
32. PINNATIFID SPLEENWORT
Asplenium pinnatifidum
Small, fronds pinnatifid, or the lower part pinnate, tapering above into a slender prolongation, stalk blackish, passing into a green rachis, fruit-dots straight or slightly curved. On rocks. Rare. P. 142.
33. BRADLEY'S SPLEENWORT
Asplenium Bradleyi
Small, once-pinnate, pinnæ lobed or toothed, stalk and rachis chestnut-brown, fruit-dots short. On rocks, preferring limestone. Very rare. P. 144.
34. WALKING FERN
Camptosorus rhizophyllus
Small, fronds undivided, heart-shaped at the base or sometimes with prolonged basal ears, tapering above to a prolonged point which roots, forming a new plant, fruit-dots oblong or linear, irregularly scattered. On shaded rocks, preferring limestone. P. 146.
35. HART'S TONGUE
Scolopendrium vulgare
Fronds a few inches to nearly two feet long, undivided, oblong-lanceolate, heart-shaped at base, fruit-dots linear, elongated. Growing among the fragments of limestone cliffs. Very rare. P. 150.
36. VIRGINIA CHAIN FERN
Woodwardia Virginica
Large, fronds once-pinnate, pinnæ pinnatifid, fruit-dots oblong, in chain-like rows parallel and near to the midrib, confluent when ripe. In swamps. P. 156.
GROUP VI
FERTILE AND STERILE FRONDS LEAF-LIKE AND USUALLY SIMILAR, FRUIT-DOTS
ROUND
37. NEW YORK FERN
Aspidium Noveboracense
Usually rather tall, fronds once-pinnate, with deeply pinnatifid pinnæ, tapering both ways from the middle, margins of fertile fronds not revolute. In woods and open meadows. P. 159.
38. MARSH FERN
Aspidium Thelypteris
Usually rather tall, fronds once-pinnate, with pinnæ deeply pinnatifid, scarcely narrower at the base than at the middle, veins forked, fertile fronds noticeable from their strongly revolute margins. In wet woods and open swamps. P. 160.
39. MASSACHUSETTS FERN
Aspidium simulatum
Close to preceding species, rather tall, fronds once-pinnate, with pinnatifid pinnæ little or not at all narrowed at base, veins not forked, margin of fertile frond slightly revolute. In wooded swamps. P. 164.
CHRISTMAS FERN
Aspidium acrostichoides
[See No. 17]
40. SPINULOSE WOOD FERN
Aspidium spinulosum var. intermedium
Very common, usually but not always large, fronds oblong-ovate, 2-3 pinnate, lowest pinnæ unequally triangular-ovate, lobes of pinnæ thorny-toothed. In woods everywhere. P. 166.
41. BOOTT'S SHIELD FERN
Aspidium Boottii
From one and a half to more than three feet high. Sterile fronds smaller and simpler than the fertile, nearly or quite twice-pinnate, the lowest pinnæ triangular-ovate, upper longer and narrower, pinnules oblong-ovate, sharply thorny-toothed. In moist woods. P. 168.
42. CRESTED SHIELD FERN
Aspidium cristatum
Usually rather large, fronds linear-oblong or lanceolate, once pinnate with pinnatifid pinnæ, linear-oblong, fruit-dots between midvein and margin. In swamps. P. 170.
43. CLINTON'S WOOD FERN
Aspidium cristatum, var. Clintonianum
In every way larger than preceding species, fronds usually twice-pinnate, pinnæ broadest at base, fruit-dots near the midvein. In swampy woods. P. 172.
44. GOLDIE'S FERN
Aspidium Goldianum
Large, fronds broadly ovate or the fertile ovate-oblong, once-pinnate with pinnatifid pinnæ, pinnæ broadest in the middle, fruit-dots very near the midvein. In rich woods. P. 174.
45. EVERGREEN WOOD FERN
Aspidium marginale
Very common, usually rather large, smooth, somewhat leathery, fronds ovate oblong, 1-2 pinnate, fruit-dots large, distinct, close to the margin. In rocky woods. P. 176.
46. FRAGRANT SHIELD FERN
Aspidium fragrans
Small, fragrant, fronds once-pinnate, with pinnatifid pinnæ, stalk and rachis chaffy, fruit-dots large. On rocks northward, especially near waterfalls. P. 178.
47. BRAUN'S HOLLY FERN
Aspidium aculeatum var. Braunii
Rather large, fronds oblong-lanceolate, twice-pinnate, pinnules sharply toothed, covered with long, soft hairs, fruit-dots small. In deep, rocky woods. P. 182.
48. COMMON POLYPODY
Polypodium vulgare
Usually small, fronds somewhat leathery, narrowly oblong, fruit-dots large, round, uncovered, half-way between midvein and margin. On rocks. P. 184.
HAY-SCENTED FERN
Dicksonia pilosiuscula
[See No. 23]
49. LONG BEECH FERN
Phegopteris polypodioides
Medium-sized, fronds downy, triangular, longer than broad, once-pinnate, pinnæ pinnatifid; lowest pair deflexed and standing forward. In moist woods and on the banks of streams. P. 187.
50. BROAD BEECH FERN
Phegopteris hexagonoptera
Larger than the preceding species, fronds triangular, as broad or broader than long, once-pinnate, pinnæ pinnatifid, lowest pair very large, basal segments of pinnæ forming a continuous, many-angled wing along the rachis. In dry woods and on hill-sides. P. 188.
51. OAK FERN
Phegopteris Dryopteris
Medium-sized, fronds thin and delicate, broadly triangular, spreading, ternate, the three divisions stalked, each division pinnate, pinnæ pinnatifid. In moist woods. P. 190.
52. BULBLET BLADDER FERN
Cystopteris bulbifera
Fronds delicate, elongated, tapering above from a broad base, 2-3 pinnate or pinnatifid, bearing fleshy bulblets beneath. On wet rocks, preferring limestone. P. 194.
53. COMMON BLADDER FERN
Cystopteris fragilis
Medium-sized, fronds thin, oblong-lanceolate, 2-3 pinnate or pinnatifid. On rocks and in moist woods. P. 198.
54. RUSTY WOODSIA
Woodsia Ilvensis
Small, more or less covered with rusty hairs, fronds lanceolate, once-pinnate, pinnæ pinnatifid. On exposed rocks. P. 200.
55. BLUNT-LOBED WOODSIA
Woodsia obtusa
Small, slightly downy, fronds broadly lanceolate, nearly twice-pinnate. On rocks. P. 202.
56. NORTHERN WOODSIA
Woodsia hyperborea
Very small, smooth or nearly so, fronds narrowly oblong-lanceolate, once-pinnate, pinnæ cordate-ovate or triangular-ovate, 5-7 lobed. On moist rocks. P. 203.
57. SMOOTH WOODSIA
Woodsia glabella
Very small, smooth throughout and delicate, fronds linear, once-pinnate, pinnæ roundish ovate, lobed. On moist rocks. P. 206.