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-foemina
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.
