1 Blades simple, unlobed and long pointed....Asplenium rhizophyllum

1 Blades pinnatifid to bipinnate................2

2 Blades pinnatifid ............Asplenium pinnatifidum

2 Blades pinnate to bipinnate-pinnatifid ..3

3 Rachis green..................4

3 Rachis black or brown.........5

4 Each frond sparse with only 2-5 pairs of pinnae, pinnae dull bluish green.....Asplenium ruta-muraria

4 Each frond with 5-20 pairs of pinnae, pinnae shiny green ...... Asplenium montanum

5 Pinnae with auricle at base.......Asplenium platyneuron

5 Pinnae without auricle at base....6

6 Rachis reddish brown at base and fading to green in distal 1/3 to 2/3............. Asplenium bradleyi

6 Rachis black or reddish brown throughout ......7

7 Rachis dark reddish brown throughout; pinnae 4-7 mm long and ovate ..... Asplenium trichomanes

7 Rachis black throughout; pinnae 6-10 mm long and oblong ............Asplenium resiliens

1 Leaves strongly dimorphic ........ 2

1 Leaves all similar ......... 3

2 Sterile blades pinnatifid to pinnate, fronds broadest near the base; veins netted .... Onoclea sensibilis

2 Sterile blades pinnate-pinnatifid, fronds tapering toward the base; veins free .... Matteuccia struthiopteris

3 Indusium attached beneath sporangia, may be inconspicuous in mature sori.......4

3 Indusium attached at the center or edge of the sori...9

4 Indusium arising up from one side and arching over sorus like a hood, not shredding but may be displaced when sorus is mature.......5

4 Indusium arising up from all sides and often shredding into small strands.........Woodsia obtusa

5 Leaf blades usually widest at or near the base, Rachis with gland-tipped hairs, .. 6

5 Leaf blades usually widest at or near the middle, Rachis without gland-tipped hairs..7

6 Rachis usually densely covered by gland-tipped hairs, often with round to oval bulblets ...Cystopteris bulbifera

6 Rachis sparsely covered by gland-tipped hairs, sometimes with irregularly shaped bulblets, petiole dark brown at base .....Cystopteris tennesseensis

7 Leaf blades broad, 2 to 3 times longer than wide Cystopteris fragilis

7 Leaf blades narrow 3 to 4 times longer than wide ... 8

8 Leaves clustered 1-4 cm back from stem apex, stem hairy ...... Cystopteris protrusa

8 Leaves clustered at stem apex, stems without hairs ........ Cystopteris tenuis

9 Indusium round, attached at center (peltate); sori round ..... Polystichum acrostichoides

9 Indusium kidney shaped (reniform) or elongate, attached laterally; sori round or elongate ..... 10

10 Indusium kidney shaped (reniform); indusium attached at sinus ..... 11

10 Indusium elongate; Indusium attached laterally ....... 17

11 Blades bipinnate-pinnatifid to tripinnate-pinnatifid ....... 16

11 Blades pinnate-pinnatifid to bipinnate .....12

12 Sori at or near leaf margins ......... Dryopteris marginalis

12 Sori borne away from leaf margins .......13

13 Fertile fronds larger and more erect than the sterile fronds; fertile pinnae twisted approximately 90^o away

from plane of leaf blade ..... Dryopteris cristata

13 Fertile fronds similar in size to sterile fronds; fertile pinnae not twisted out of plane of leaf

blade.......14

14 Sori closer to midvein of pinnule than to the margin ...... Dryopteris goldiana

14 Sori found half-way between midvein and margin of pinnule ... 15

15 Blades narrow, usually less than 20 cm wide; Scales at base of petioles with dark brown stripe in the

center ...... Dryopteris clintoniana

15 Blades wider, usually greater then 20 cm wide; Scales at base of petioles tan ...... Dryopteris celsa

16 First lower pinnule of the basal pinna no longer than the adjacent pinnule; Indusium with small glands

...... Dryopteris intermedia

16 First lower pinnule of the basal pinna longer than the adjacent pinnule;Indusium without small glands Dryopteris carthusiana

17 Leaves pinnate ....... Diplazium pycnocarpon

17 Leaves pinnate-pinnatifid to tripinnate-pinnatifid ...... 18

18 Blades pinnate-pinnatifid ....... Deparia acrostichoides

18 Blades bipinnate to tripinnate ..... Athyrium felix-femina

1 Sterile blade entire, net-veined, sporangia embedded on short straight stalk ..... 2

1 Sterile blade pinnate to bipinnate pinnatifid; free veined; sporangia stalked on pinnately branched stalk....

2 Veins in leaves forming small network within larger networks ....... Ophioglossum engelmannii

2 Veins in leaves with incomplete small network within larger networks ...... 3

3 Blades dark green, firm persistant basal sheath, found in shaded woody areas ....... Ophioglossum vulgatum

3 Blades pale green, thin herbaceous basal sheath, found in open areas such as meadows, marshes etc. .... Ophioglossum pusillum

4 Leaf blades large, 5 - 25 cm long, ..... 5

4 Leaf blades small, 2 - 4 cm long, ...... 9

5 Leaf blades sessile, fertile stalk arising from stipe at base of blade ..... Botrychium virginianum

5 Leaf blades long stalked, fertile frond arising from stipe well below the base of the blade ...... 6

6 Terminal pinnules noticebly larger than the lateral pinnules ...... 7

6 Terminal pinnules approximately the same size as lateral pinnules ...... Botrychium multifidum

7 Sterile blade mostly bipinnate, pinnae sharply serrate not dissected ...... Botrychium biternatum

7 Sterile blade mostly tripinnate, pinnae slightly serrate to highly dissected, ......

8 Terminal segments rounded at tip ..... Botrychium oneidense

8 Terminal segments pointed at tip ...... Botrychium dissectum

9 Blade undivided to pinnate ..... Botrychium simplex

9 Blade pinnate-pinnatifid to bipinnate ...... Botrychium matricariifolium

1 Fertile and sterile pinnae on seperate fronds ... Osmunda cinnamomea

1 Fertile and sterile pinnae on the same fronds ... 2

2 Fertile pinnae at tip of frond, frond bipinnate ... Osmunda regalis

2 Fertile pinnae in the middle of fron, frond pinnate-pinnatafid .. Osmunda claytoniana

1 Lower surface of blades and petiole with numerous scurfy brownish scales .... Pleopeltis polypodioides

1 Lower surface of blades and petiole without scales... Polypodium virginianum

1 Sori short and distinct... Adiantum pedatum

1 Sori continuous along leaf margin.... 2

2 Blades pubescent beneath, pinnae bipinnate pinnatifid, individual pinnae round to oval.....Cheilanthes lanosa

2 Blades glabrous beneath, pinnae bipinnate, individual pinnae lanceolate....... 3

3 Stipe and rachis very pubescent, fertile pinnae narrower than sterile pinnae .... Pellaea atropurpurea

3 Stipe and rachis glabrous to slighlty pubescent, fertile pinnae approximately the same width ....... Pellaea glabella

1 Blades triangular, widest at base, rachis winged, indusium absent...2

1 Blades lanceolate, narrowing at base, rachis not winged, indusium present..3

2 Rachis not winged above the two basal pinna pairs, ....Phegopteris connectilis

2 Rachis winged between all pinna pairs .. Phegopteris hexagonoptera

3 Lower pinnae much smaller than middle pinnae... Thelypteris noveboracensis

3 Lower pinnae slightly smaller than or same size as middle pinnae.. Thelypteris palustris