Part 3

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.

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. 175.

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.

FERN DESCRIPTIONS

"Nature made a fern for pure leaves."--_Thoreau_

GROUP I

STERILE AND FERTILE FRONDS TOTALLY UNLIKE; FERTILE FRONDS NOT LEAF-LIKE IN APPEARANCE

1. SENSITIVE FERN

_Onoclea sensibilis_

Newfoundland to Florida, in wet meadows.

_Sterile fronds._--One or two inches to three feet high, broadly triangular, deeply cut into somewhat oblong, wavy-toothed divisions, the lower ones almost reaching the midrib, the upper ones less deeply cut; _stalk_ long.

_Fertile fronds._--Quite unlike the sterile fronds and shorter, erect, rigid, contracted; _pinnules_ rolled up into dark-green, berry-like bodies which hold the spore-cases; appearing in June or July.

This is one of our commonest ferns, growing in masses along the roadside and in wet meadows. Perfectly formed sterile fronds are found of the tiniest dimensions. Again the plant holds its own among the largest and most effective ferns. From its creeping rootstock rise the scattered fronds which at times wear very light and delicate shades of green. There is nothing, however, specially fragile in the plant's appearance, and one is struck by the inappropriateness of its title. It is probable that this arose from its sensitiveness to early frosts.

Though one hesitates to differ from Dr. Eaton, who described the fertile fronds as "nearly black in color" and said that they were "not very common," and that a young botanist might "search in vain for them for a long time," my own experience has been that the fresh ones are very evidently green and neither scarce nor specially inconspicuous.

I have found these fertile fronds apparently full-grown in June, though usually they are assigned to a much later date. They remain standing, brown and dry, long after they have sown their spores, side by side with the fresh fronds of the following summer.

Detail _a_ in Plate I represents the so-called _var. obtusilobata_. This is a form midway between the fruiting and the non-fruiting fronds. It may be looked for in situations where the fern has suffered some injury or deprivation.

2. OSTRICH FERN

_Onoclea Struthiopteris_

Nova Scotia to New Jersey, along streams and in moist woods. Growing in a crown, two to ten feet high.