Key to the true ferns and fern allies of Tennessee
- 1 Key to the Pteridophytes
- 2 Fern Ally
- 3 2
- 4 3
- 5 True Fern
- 6 4
- 7 5
- 8 6
- 9 7
- 10 8
- 11 9
- 12 10
- 13 11
- 14 12
- 15 13
- 16 14
- 17 15
- 18 16
- 19 17
- 20 18
- 21 Aspleniaceae
- 22 ASP1
- 23 ASP2
- 24 ASP3
- 25 ASP4
- 26 ASP5
- 27 ASP6
- 28 ASP7
- 29 Blechnaceae
- 30 Dennstaedtiaceae
- 31 Dryopteridaceae
- 32 Dryopteris
- 33 DRY1
- 34 DRY2
- 35 DRY3
- 36 DRY4
- 37 DRY5
- 38 Equisetaceae
- 39 Hymenophyllaceae
- 40 Trichomanes
- 41 TRI1
- 42 Isoetaceae
- 43 ISO1
- 44 ISO2
- 45 ISO3
- 46 ISO4
- 47 Lycopodiaceae
- 48 LYC2
- 49 LYC3
- 50 LYC4
- 51 LYC5
- 52 Dendrolycopodium
- 53 LYCden1
- 54 Diphasiastrum
- 55 Huperzia
- 56 LYChup1
- 57 Lycopodiella
- 58 Marsileaceae
- 59 Ophioglossaceae
- 60 OPH1
- 61 OPH2
- 62 Botrychium
- 63 Ophioglossum
- 64 OPHoph1
- 65 Sceptridium
- 66 OPHsce1
- 67 OPHsce2
- 68 Osmundaceae
- 69 Osmunda
- 70 Polypodiaceae
- 71 Polypodium
- 72 Pteridaceae
- 73 PTE1
- 74 PTE2
- 75 Adiantum
- 76 Cheilanthes
- 77 PTEche1
- 78 Pellaea
- 79 Selaginellaceae
- 80 Thelypteridaceae
- 81 THE1
- 82 Phegopteris
- 83 Thelypteris
- 84 THEthe1
- 85 Woodsiaceae
- 86 WOO1
- 87 WOO2
- 88 WOO3
- 89 Cystopteris
- 90 WOOcys1
- 91 WOOcys2
- 92 Woodsia
Key to the Pteridophytes
- True Fern: Leaves usually foliaceous with branching veins. Sporangia on leaves or appendages of leaves (never in leaf axils, cones, or cavities at the base of leaves
- Fern Ally: Leaves needle-like or scale-like with only a single midvein. Never foliaceous and young plants never have fiddleheads. Sporangia are in leaf axils, strobili, or cavities at the base of leaves.
- Isoetaceae: Heterosporous. No aerial stems. Leaves needle-like and arising from a corm. Sporangia in cavities near the base of leaves at or below ground level.
- 2: aerial stems present, leaves absent, scale-like, or forming a sheath around the stem at nodes.
- Equisetaceae: aerial stems hollow or fluted. Prominent joints unbranched or with nodal whorls of several branches. Strobili terminal.
- 3: aerial stems not hollow or fluted. Leaves small, spiraled, scale-slike.
- Selaginellaceae: Leaves with ligules. Spores in a flat or 4-sided strobilus. Heterosporous.
- Lycopodiaceae: Leaves without ligules. Spores in leaf axils or in terminal strobili. Homosporous.
- 4: Plant aquatic or rooting where water usually would be if water levels are low.
- 5: Plant terrestrial or rooting on rocks or trees.
- Marsileaceae: Leaves needle-like or clover-like. Usually rooted in mud
- Azolla caroliniana: Leaves with thalli, not clover-like. Stems floating.
- 6: Leaves with thalli and usually less than a centimeter squared in total size
- 7: Leaves much larger than a centimeter squared without thalli.
- Hymenophyllaceae: Leaves with veins or filamentous strands. Spores in tubular indusia
- Pteridaceae: Leaves without veins or spores. Usually have a fringe of filamentous projections.
- Ophioglossaceae: Sporangia fused laterally into two rows on upright spikes or panicles on petiole above vegetative blade.
- 8: Sporangia not fused.
- 9: Fertile leaves appear to lack blade tissue
- 10: Sporangia on margin or underside of flat parts, fertile parts green.
- Osmundaceae: Leaves pinnate or more complex. Spores borne singly on axes of leaflets or pinnae.
- Onoclea sensibilis: Leaves pinnatifid. Sporangia borne in clusters.
- Lygodium palmatum: Leaves climbing by a vine-like midrib. Rhizome is terrestrial, hairy, and without scales.
- 11: Leaves free-standing, not vine-like.
- 12: Sori beneath the rolled up edge of leaflets.
- 13: Sori without indusium or beneath a film or scale of tissue
- Dennstaedtiaceae: Leaf blades generally over 30 centimeters long. Rhizome wide-creeping, hairy, and without scales.
- Pteridaceae: Leaf blades generally over 30 centimeters long, clustered on a short, ascending, scaly rhizome.
- 14: Long sori within a linear indusium
- 15: Sori generally round, kidney-shaped, or densely gathered, covering the lower leaf surface.
- Blechnaceae: Sori in one row on each side of leaf rib, lined end to end.
- 16: Sori generally solitary and not end to end
- Aspleniaceae: Glossy and wiry petiole with a deep red to black color.
- Woodsiaceae: Petiole green to straw colored; not glossy or wiry.
- Thelypteridaceae: Small, needle-like hairs present on rib, veins, and groove of petiole.
- 18: No hairs present on rib, veins, or groove of petiole.
- Woodsiaceae: Indusium pocket-like attached beside the sorus or ring of scale-like indusium portions aroud the edge of sorus.
- Dryopteridaceae: Indusium kidney shaped or lepidote, rising above the sorus.
- Asplenium rhizophyllum: Leaves rooting at the tips. Veins joined by cross-veins to form a network.
- ASP3: Leaves not rooting at the tips. Veins free.
- Asplenium scolopendrium: Leaves simple, heart-shaped at the base, and linear to lanceolate.
- Asplenium pinnatifidum: Leaves pinnatifid and triangular.
- Asplenium platyneuron: Leaflets alternate, nearly sessile, and with bases that overlap the midrib.
- ASP6: Leaflets opposite and without petiolules
- Asplenium ruta-muraria: Plant with ovate to triangular leaves, green petioles, hairy indusia, and bluish living material
- ASP7: Plant with dark petioles, entire indusia, and green living material
- Asplenium resiliens: Leaflets six to ten millimeters long, three to five times as long as wide, and generally widest at the base.
- Asplenium trichomanes: Leaflets four to seven millimeters long, one to two times as long as wide, and generally widest above the base.
- Asplenium montanum: Leaf blades twice-pinnate throughout. Petiole all pale except at the base.
- Asplenium bradleyi: Leaf blades twice pinnate only near base. Petiole dark reddish-brown.
- Woodwardia areolata: Sterile leaves pinnate at the base, sometimes pinnatifid. Fertile leaves more erect and contracted.
- Woodwardia virginica: Sterile and fertile leaves pinnate-pinnatifid throughout.
- Pteridium aquilinum: Sori long to marginal, continuous beneath curled leaf edge. Leaves without hair or glands on stipes.
- Dennstaedtia punctilobula: Sori round and discontinuous. Leaves with trichomes on stipes.
- Polystichum acrostichoides: Spores covering entire lower surface of leaves where present. Indusia round and shield-like; with stalk attached to the lower surface.
- Dryopteris: Spores never covering entire lower surface of leaves. Indusia are kidney-shaped and attached within the sinus of the kidney-shaped sorus.
- DRY1: Leaves pinnate-pinnatifid to twice pinnate at the base
- DRY2: Leaves are twice pinnate to three times pinnate-pinnatifid at the base
- Dryopteris marginalis: Petioles have a dense tuft of tawny scales at the base. The sori are at or near the leaf edges.
- DRY3: Petioles have tan to dark brown scales at the base. Sori not on the leaf edges.
- Dryopteris intermedia: Leaves more or less evergreen with the previous year's leaves usually next to leaves of current year. Glands on stipes present on rachis and leaflet midribs.
- DRY4: Leaves deciduous. No glands on stipes present.
- Dryopteris cristata: Fertile leaves erect and linear to lanceolate. Fertile leaves two to three times as long as vegetative leaves.
- DRY5: Basal leaflets ovate. Petiolar scales dark brown or with a dark brown stripe.
- Dryopteris carthusiana: Indusium without hair. Leaves are ovate to lanceolate.
- Dryopteris campyloptera: Indusium occasionally with glands. Leaves are ovate to triangular.
- Dryopteris goldiana: Sori are closer to the midvein than the leaflet edge. Leaves narrow abruptly near the top.
- Dryopteris celsa: Sori are halfway between the midvein and leaflet edge. Leaves gradually narrow near the top.
- Equisetum arvense: Fertile stem unbranched and without chlorophyll. Sterile stems have many circular arrangements of secondary branches.
- Equisetum hyemale: Fertile and sterile stems similar and usually unbranched or with few branches.
- Hymenophyllum tayloriae: Thalloid gametophyte ribbon-like, irregular, and branched, usually fringed with very small finger-like projections.
- Trichomanes: Sporophytes between thalloid and typical fern habit with bristles on margins or a single row of filamentous gametophytes
- Trichomanes intricatum: Uniseriate filamentous gametophyte
- TRI1: Thalloid or fern-like sporophytic plants
- Trichomanes boschianum: Leaves pinnately lobed to compound.
- Trichomanes petersii: Leaves more or less thalloid and leaflets entire to slightly lobed.
- ISO1: Aquatic plants
- ISO2: Terrestrial plants, though sometimes found in shallow waters, especially during rainy seasons.
- Isoetes valida: A curtain-like membrane covers more than half of spores.
- ISO3: A curtain-like membrane covers less than a quarter of spores.
- Isoetes melanopoda: Leaves black near the base.
- Isoetes butleri: Leaves greenish-brown near the base.
- Isoetes appalachiana: A curtain-like membrane covers 20 to 25 percent of sporangia.
- ISO4: A curtain-like membrane covers 10 to 20 percent of sporangia.
- Isoetes engelmannii: Megaspores are 380 to 508 micrometers in diameter.
- Isoetes tennesseensis: Megaspores are 616 to 946 micrometers in diameter.
- Huperzia: Fertile leaves similar to sterile leaves
- LYC2: Fertile leaves broader, shorter, or more spreading than sterile leaves.
- Lycopodiella: Plants in wet soils. Rhizome dies back annually.
- LYC3: Plants in dry soils. Rhizome persistent and trailing.
- LYC4: Erect leafy stems are over a centimeter in diameter.
- LYC5: Erect leafy stems are 2 to 8 millimeters in diameter.
- Spinulum annotinum: One strobilus per erect stem. Strobili are sessile.
- Lycopodium clavatum: One to six strobili per erect stem. Strobili on peduncles.
- Diphasiastrum: Strobili are on long narrow peduncles. Leaves are scale-like and appressed to the stem. Leafy branches are usually less than 3 millimeters wide.
- Dendrolycopodium: Strobili are sessile. Leaves are awl-shaped. Leafy branches are usually five to eight millimeters wide.
- Dendrolycopodium obscurum: Leaves are unequal in size. Upright stems flat.
- LYCden1: Leaves equal in size. Upright stems round.
- Dendrolycopodium hickeyi: Leaves dark green, appressed, and not prickly.
- Dendrolycopodium dendroideum: Leaves are pale green, spreading, and prickly.
- Diphasiastrum digitatum: Terminal fronds flat in cross-section and usually green.
- Diphasiastrum tristachyum: Terminal fronds square in cross-section and bluish
- Huperzia lucidula: Leaves narrowly obovate and one to eight toothed.
- LYChup1: Leaves lanceolate or oblanceolate. Leaves are entire or with one to three short teeth.
- Huperzia appressa: Leaf margins entire or with occasional papillae. Usually found at high elevations in igneous substrates.
- Huperzia porophila: Leaf margins few papillae or large teeth. Usually found at mid to low elevations in sandstone.
- Lycopodiella appressa: Erect stems are less than 4 millimeters in diameter. Leaves of peduncle and strobilus appressed and entire.
- Lycopodiella alopecuroides: Erect stems over 6 millimeters in diameter. Leaves of peduncle incurved an those of the strobilus are spreading with ciliate margins.
- Pilularia americana: Leaves thread-like and lack expanded blade tissue
- Marsilea minuta: Palmately divided leaves with long petioles, appearing clover-like
- Sceptridium: Common petiole of sterile and fertile leaf portions terminating near the ground.
- OPH2: Common petiole of sterile and fertile leaf portions rising well above the ground.
- Botrypus virginianus: Sterile blade broadly triangular, ternate to 2 or 3 pinnate, and herbaceous
- Botrychium: Sterile blade narrowly triangular or elliptic, pinnatifid to pinnate, and fleshy-herbaceous
- Botrychium simplex: Sterile leaves nearly simple to pinnatifid
- Botrychium matricariifolium: Sterile leaves once to twice pinnate
- Ophioglossum crotalophoroides: Sterile portion of blade lying on the ground, triangular to heart-shaped
- OPHoph1: Sterile portion of blade erect to spreading, ovate to lanceolate
- Ophioglossum engelmannii: Veins of leaf blade forming small areoles within larger areoles. Usually in calcium rich soil.
- Ophioglossum pycnostichum: Veins of leaf blade not different in size or prominence. Usually in neutral soil.
- Sceptridium jenmanii: Lower leaflets long-petiolulate and clearly alternate
- OPHsce1: Lower leaflets short-petiolulate and opposite to subopposite
- Sceptridium oneidense: Terminal segments of sterile blade ovate, obovate, or rhombic with blunt or rounded apex.
- OPHsce2: Terminal segments of sterile blade lanceolate to lance-ovate with an acute apex.
- Sceptridium biternatum: Sterile blades mostly twice pinnate.
- Sceptridium dissectum: Sterile blades mostly three times pinnate.
- Osmundastrum cinnamomea: Fertile leaves with monomorphic pinnae
- Osmunda: Fertile leaves with dimorphic pinnae
- Osmunda claytoniana: Leaves pinnate-pinnatifid. Fertile pinnae in the middle of the blade.
- Osmunda regalis: Leaves twice pinnate. Fertile pinnae at the terminal end of the blade.
- Pleopeltis polypodioides: Blades with numerous peltate scales on underside of leaf
- Polypodium: Blades either lacking peltate scales or only associated with midrib.
- Polypodium appalachianum: Leaf blade widest at base. Leaf tips narrowly rounded to acute. Stem scales are golden brown
- Polypodium virginianum: Leaf blade widest in the middle. Leaf tips rounded to obtuse. Stem scales are dark brown.
- Vittaria appalachiana: Plants thalloid; leaf area less than 1 centimeter squared
- PTE1: Plants not thalloid; leaf area much larger than one centimeter squared.
- Adiantum: Sori round or oblong; sori distinct along leaf edge.
- PTE2: Sori continuous along leaf edge.
- Pellaea: Leaves without hair or with very little hair. Leaf edges strongly reflexed. Terminal segments over eight millimeters long.
- Cheilanthes: Leaves hairy. Margins recurved. Terminal segments one to four millimeters long.
- Adiantum capillus-veneris: Leaves pinnate
- Adiantum pedatum: Leaves dichotomously branching like a fan
- Cheilanthes alabamensis: Leaf segments without hair or with very few hairs
- PTEche1: Leaf segments covered with villae or downy hairs
- Cheilanthes tomentosa: Leaves three times pinnate. Stipe and rachis have flattened white scales.
- Cheilanthes lanosa: Leaves twice or three times pinnate. Stipe and rachis have hair, but don't have scales.
- Pellaea atropurpurea: Petiole and rachis dull and sparsely or not hairy.
- Pellaea glabella: Petiole and rachis shiny and hairy.
- Selaginella rupestris: Leaves in spirals with obvious bristle-tips
- Selaginella apoda: Leaves four-ranked, but not in spirals or bristle tipped.
- Phegopteris: Leaves bipinnatifid, less than twice as long as wide. Rachis with adnate pinnae wings. Sori without indusia
- THE1: Leaves pinnately dissected and easily twice as long as wide. Rachis without adnate pinnae wings. Sori with indusia
- Thelypteris: Leaves pinnate to pinnate-pinnatifid. Costae with an adaxial groove.
- Macrothelypteris torresiana: Leaves twice to three times pinnate. Costae lacking an adaxial groove.
- Phegopteris hexagonoptera: Rachis has a continuous wing between the two basal pairs of pinnae. Leaves are about as long as wide.
- Phegopteris connectilis: Rachis wing is interrupted between the two basal pairs of pinnae. Leaves are about twice as long as wide.
- Thelypteris noveboracensis: Medial pinnae over four times longer than basal most pinnae
- THEthe1: Medial pinnae about equal in length to basal pinnae
- Thelypteris simulata: Underside of leaves have resin glands. Costae lack scales. Lateral veins of pinnae lobes are not forked.
- Thelypteris palustris: Underside of leaves do not have glands, but have tan scales. Lateral veins of pinnae lobes are branching.
- Woodsia: Indusium is cuplike, composed of scale-like or filamentous segments
- Cystopteris: Indusium is hoodlike, arching over the sorus. It is attached to the lamina on one side only.
- Athyrium filix-femina: Sori is crescent or J-shaped. Leaves are twice or three times pinnate.
- WOO3: Sori is straight or slightly curved. Leaves are pinnate to pinnate-pinnatifid.
- Deparia acrostichoides: Midrib is silvery and hairy. Leaves are pinnate-pinnatifid.
- Diplazium pycnocarpon: Midrib is without hair. Leaves are pinnate.
- WOOcys1: Rachises and costae have glandular hairs. Leaves are widest at or near the base.
- WOOcys2: Rachises and costae do not have glandular hairs. Leaves are widest near the middle.
- Cystopteris bulbifera: Rachises and costae densely covered with glandular hairs.
- Cystopteris tennesseensis: Rachises and costae sparsely covered with glandular hairs.