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Key A3: lycophytes and pteridophytes with leaves not ‘fern-like’ (unlobed, variously awl-shaped, scale-like, or terete)

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1 Stem obviously jointed; leaves scale-like, borne in a whorl at each of the distant joints; spores borne in a terminal strobilus with peltate scales
1 Stem (or rhizome) not jointed; leaves scale-like or larger, but if scale-like not borne in whorls at distant joints; spores borne variously, but if in a terminal strobilus the scales not peltate.
..2 Leaves linear, grass-like, 1-60 cm long, 20× or more as long as wide.
....3 Leaves solitary (though often the internodes very short from a thin, creeping rhizome); sporangia borne in a spherical (ca. 3 mm in diameter) sporocarp on a separate branch from the rhizome
....3 Leaves numerous from a corm or short-creeping rhizome; sporangia either borne in the expanded leaf bases (Isoetes in ISOETACEAE) or in 2 rows at the tip of the linear fertile leaves (Schizaea in SCHIZAEACEAE), or in a sub-marginal groove on either side of the midrib (Vittaria in PTERIDACEAE).
......4 Leaves straight and stiff, arching, or flaccid, from a 2-3-lobed corm; sporangia borne in the expanded, hyaline leaf bases
......4 Leaves either straight and stiff or notably spiral-curly, from a short-creeping rhizome; sporangia borne in 2 rows either at the expanded pectinate tip of the fertile leaves or along much of the length of the linear leaves.
........5 Leaves 10-60 cm long, straight, stiff; plants epiphytic or rarely epipetric, the leaves pendent
........5 Leaves 1-12 cm long, spiral-curly; plants terrestrial in peaty substrate, the leaves erect
..2 Leaves various (scale-like, awl-like, moss-like, or flat), but not linear and grass-like, mostly 1-10 (-20)× as long as wide.
..........6 Leaves inconspicuous, reduced to a few nerveless scales (< 1.5 mm long), the internodes much longer than the leaves; sporangia yellowish, 3-locular, 1-2 mm in diameter; stems upright, repeatedly branched dichotomously
..........6 Leaves either larger or, if scale-like, with 1 or more nerves and longer than the internodes (the leaves thus overlapping); sporangia yellowish to brownish, 1-locular, < 1 mm in diameter; stems either subterranean or surficial rhizomes or erect or ascending (and sometimes dichotomously branched in whole or in part in Huperzia in HUPERZIACEAE, and Diphasiastrum and Dendrolycopodium in LYCOPODIACEAE).
............ 7 Plant with leaves very numerous and overlapping along the creeping, ascending, erect, or pendant stems, the leaves scale-like or awl-like, 0.5-2 (-3) mm wide, typically acute, acuminate, or hair-tipped; sporangia either in terminal strobili (axillary to specialized, smaller leaves) or axillary to normal leaves; [Lycophytes].
............ ..8 Sporangia borne in flattened or quadrangular strobili sessile at the tips of leafy branches; spores and sporangia each of two sizes, the megasporangia larger and borne basally in the strobili
............ ..8 Sporangia borne either in the axils of normal foliage leaves, or in strobili sessile at the tips of leafy branches or stalked on specialized branches with fewer and smaller leaves; spores and sporangia each of one size.
............ ....9 Leafy stems erect or pendant, simple or dichotomously branched, the ultimate branches vertically oriented (upwards or downwards); sporophylls like the sterile leaves or only slightly reduced, in annual bands along the stem; vegetative reproduction by leafy gemmae near the stem apex (Huperzia) or lacking gemmae (Phlegmariurus)
............ ....9 Leafy stems prostrate or erect, if erect then generally branched, the ultimate branches spreading (horizontal) or ascending; sporophylls differing from sterile leaves, either broader and shorter, or more spreading, aggregated into terminal cones; lacking vegetative reproduction by gemmae.
............ 7 Plant with leaves not as above (see below for details); [Pteridophytes].
............ ......10 Leaves palmately lobed.
............ ........11 Leaves divided into separate sterile and fertile segments, the sterile leaf blade 30-90 cm long, ovate to lanceolate, entire-margined, obtuse, the longer fertile portion with 2 rows of sporangia somewhat imbedded in it
............ ........11 Leaves with fertile portions in patches near the tips of the lobes
............ ......10 Leaves unlobed (or if lobed, pinnately so).
............ ..........12 Plant with 1 (-several) leaves, divided into separate sterile and fertile segments, the sterile leaf blade 0.3-90 cm long, ovate to lanceolate, entire-margined, unlobed, obtuse, the longer fertile portion with 2 rows of sporangia somewhat imbedded in it
............ ..........12 Plant with many leaves, generally 5 or more, not divided into separate sterile and fertile segments, the leaves either (a) small, 0.3-1.6 cm long, obovate, scattered along a very thin creeping rhizome, or (b) larger, (2-) 8-30 cm long, cordate at base, the tip long-attenuate (often proliferous, bearing a plantlet at the tip).
............ ............ 13 Leaf blades (2-) 8-30 cm long, cordate at the base, the tip long-attenuate, often proliferous (bearing a plantlet at the tip); sporangia grouped into indusiate sori on the undersurface; leaf texture moderately thick; rhizome erect or ascending, 1.0-1.5 mm in diameter, the leaves clustered from its tip
............ ............ 13 Leaf blades 0.3-15 cm long, cuneate at the base, acute to rounded or obtuse at the tip, not proliferous; sporangia solitary in a marginal pocket on the leaf; leaf texture very thin; rhizome creeping on the surface of rock or bark, either 0.1-0.3 or 0.5-1.5 mm in diameter, the leaves scattered along it
............ ............ ..14 Leaf blades 0.3-1.6 cm long; sporangia solitary in a marginal pocket on the leaves; leaf texture very thin; rhizome 0.1-0.3 mm in diameter
............ ............ ..14 Leaf blades 2-15 cm long; sporangia borne in round sori on the lower surface of the leaves; leaf texture herbaceous to subcoriaceous; rhizome 0.5-1.5 mm in diameter

Key A4: small ‘fern-like’ pteridophytes, epipetric or epiphytic, growing on rock, tree bark, or walls

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1 Leaves pinnatifid or bipinnatifid, the pinnae not fully divided from one another (the rachis winged by leaf tissue most or all of its length).
..2 Leaves pinnatifid, the pinnae not lobed.
....3 Leaf blades with a long-attenuate apex, blade lobed for up to 2/3 its length; sori elongate
....3 Leaves without a long-attenuate apex, blade lobed for > 4/5 of its length; sori round
..2 Leaves bipinnatifid, at least the lowermost pinnae deeply lobed.
......4 Leaves of a very delicate texture, 1 cell thick; sori borne in cups on the leaf margins; [rock outcrops with high air humidity]
......4 Leaves of an herbaceous, subcoriaceous, or coriaceous texture, > 1 cell thick; sori otherwise; [various habitats, not strictly of moist sites].
........5 Leaf blades 1-7 cm long, hairy with some hairs > 1 mm long
........5 Leaf blades > 7 cm long, glabrescent or hairy with hairs < 1 mm long.
..........6 Lowermost (and other) pinnae with numerous, rather even lobes
..........6 Lowermost pinnae with a few, irregular lobes (the upper pinnae unlobed)
1 Leaves pinnate, pinnate-pinnatifid, 2-pinnate, or even more divided, to 5-pinnate (the rachis naked for most of its length, often winged in the apical portion).
............ 7 Leaves pinnate or pinnate-pinnatifid.
............ ..8 Leaves of a very delicate texture, 1 cell thick; sori borne in cups on the leaf margins; [rock outcrops with high air humidity]
............ ..8 Leaves of an herbaceous, subcoriaceous, or coriaceous texture, > 1 cell thick; sori otherwise or sporangia not grouped in sori; [various habitats, not strictly of moist sites].
............ ....9 Pinnae > 1 cm wide; leaves subcoriaceous to coriaceous
............ ......10 Sporangia borne on 2 specialized fertile pinnae (in rows on segments of the 2 basalmost fertile pinnae of the leaf); [native; TX westwards]
............ ......10 Sporangia borne on the lower surface of green leaves; [collectively widespread]
............ ........11 Veins free; [native; s. FL]
............ ........11 Veins anastamosing (rejoining one another) to form a netlike pattern of areoles.
............ ..........12 Costae with a groove on the upper side, sometimes with tan, filiform scales; margins of segments denticulate, crenate, or spinulose
............ ..........12 Costae rounded or flat on the upper side, with red, multicellular hairs; margins of segments entire or with rounded lobes
............ ....9 Pinnae < 1 cm wide; leaves herbaceous to subcoriaceous.
............ ............ 13 Sori on the undersurface of the leaf, located away from the margins
............ ............ 13 Sori on the undersurface of the leaf, marginal and more-or-less hidden beneath either the unmodified revolute leaf margin or under a modified, reflexed false indusium
............ 7 Leaves bipinnate or more divided.
............ ............ ..14 Leaf blade pentagonal, broadly triangular, or narrowly triangular in outline, ca. 1-2.5× as long as wide.
............ ............ ....15 Leaf blade narrowly triangular in outline, mostly 2-2.5× as long as wide.
............ ............ ......16 Sporangia borne either in many sori on fertile blades or on fertile pinnules borne at the base of the otherwise sterile blades
............ ............ ......16 Sporangia borne in a solitary sorus terminal on the truncate apex of wedge-shaped leaf segments
............ ............ ....15 Leaf blade either ovate, pentagonal, or broadly triangular in outline, mostly 0.8-2× as long as wide.
............ ............ ........17 Leaves dimorphic, fertile leaves with longer and narrower segments than the sterile leaves
............ ............ ..........18 Leaf segments strongly revolute; sporangia scattered along veins or submarginal, not grouped into indusiate sori; lower surface of leaf segments either densely covered with a whitish farina or distinctly bluish-green
............ ............ ..........18 Leaf segments planar; sporangia borne in round, indusiate sori; lower surfaces of leaf segments green.
............ ............ ............ 19 Leaf blade pentagonal in outline, the terminal pinna by far the largest; rhizome 5-8 mm in diameter; indusia present, thick, persistent, and reniform; [introduced species, rarely naturalized]
............ ............ ............ 19 Leaf blade broadly triangular in outline, the basal pinnae by far the largest; rhizome ca. 1 mm in diameter; indusia absent; [native species of mountain peaks from n. NC and VA northwards]
............ ............ ..14 Leaf blade elongate, mostly lanceolate, generally > 4× as long as wide (except in Adiantum, with leaf blade often only 1.5-3× as long as wide, but not notably triangular or pentagonal in outline).
............ ............ ............ ..20 Sori marginal, usually more-or-less hidden under the revolute margin of the pinnule
............ ............ ............ ..20 Sori not marginal, either exposed, or slightly to strongly hidden by indusia.
............ ............ ............ ....21 Leaf blades 3-12 cm long; sori elongate, covered by a flap-like, entire indusium
............ ............ ............ ....21 Leaf blades 4-30 (-50) cm long; sori globular, surrounded or covered by an entire, ciliate, or divided indusium.
............ ............ ............ ......22 Veins reaching the margin; indusium attached under one side of the sorus, hood-like or pocket-like, arching over the sorus; petioles glabrous or sparsely beset with scales, the petiole bases not persistent
............ ............ ............ ......22 Veins ending short of the margin; indusium attached under the sorus, either cup-like (divided into 3-6 lanceolate to ovate lobes which surround the sorus from below) or of minute numerous septate hairs, which extend out from under the sorus on all sides; petioles often densely beset with scales, the petiole bases persistent

Key A6: medium to large ‘fern-like’ pteridophytes, epipetric on rock or walls, or epiphytic on tree trunks

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1 Leaf vine-like, 0.3-10 m long, the branching dichotomous, 1 branch of each dichotomy terminating in a pair of pinnae, the pinnae often widely spaced (> 10 cm apart)
1 Leaf not vine-like, 0.3-3 m long, the branching not as described above, the pinnae regularly and more-or-less closely spaced (mostly < 10 cm apart).
..2 Leaves (at least the sterile leaves if the leaves are dimorphic) 1-pinnate-pinnatifid or less divided (the pinnae entire, toothed, lobed or pinnatifid).
....3 Leaves dimorphic, the sterile leaves 1-pinnate, the fertile leaves bipinnate; sori covering the entire undersurface of the fertile leaves
....3 Leaves monomorphic; sori not covering the undersurface of the leaves.
......4 Sori marginal, continuous, covered by a reflexed false indusium along the leaf margin; pinnae usually opposite, linear, not toothed or lobed
......4 Sori neither marginal nor continuous, slightly to entirely covered by an elongate or roundish indusium (sometimes ciliate, toothed, or divided into narrow segments); pinnae usually at least in part alternate, mostly lanceolate, toothed, lobed, or pinnatifid.
........5 Sori elongate, the indusium flap-like, attached along the side; leaf blades < 7 cm wide when > 30 cm long
........5 Sori circular or globular, the indusium peltate, reniform, or cuplike; leaf blades > 5 cm wide when > 30 cm long.
..........6 Leaves pinnatifid
..........6 Leaves 1-pinnate or, 1-pinnate-pinnatifid, or 2-pinnatifid.
............ 7 Leaves 1-pinnate, the pinnae toothed and each with a slight to prominent lobe near the base on the side toward the leaf tip; indusia peltate, reniform, or crescent-shaped.
............ ..8 Leaves pale green, thin in texture; pinnae articulate to rachis, deciduous with age; rhizome bearing elongate, thin, wiry stolons; indusia reniform or crescent-shaped
............ ..8 Leaves dark-green, subcoriaceous to coriaceous; pinnae not articulate and deciduous with age; rhizome not producing stolons; indusia peltate
............ ....9 Segment margins
............ ....9 Segment margins serrate or spinulose
............ 7 Leaves 1-pinnate-pinnatifid or 2-pinnatifid, the pinnae pinnatifid, generally lacking a prominent basal lobe; indusia either reniform or cuplike.
............ ......10 Vascular bundles in the petiole 3-7
............ ......10 Vascular bundles in the petiole 2.
............ ........11 Indusium reniform, arching over the sorus
............ ........11 Indusium cuplike, attached beneath the sorus and consisting of 3-6 lanceolate to ovate segments
..2 Leaves (at least the sterile leaves if the leaves are dimorphic) 2-pinnate or more divided (the pinnae divided to their midribs).
............ ..........12 Pinnae dimorphic, sori limited to the basal 2 pinnae
............ ..........12 Pinnae not dimorphic.
............ ............ 13 Sori marginal and borne on the underside of the false indusium (modified, marginal flaps of the leaf margin); petioles and rachis shiny black or reddish-black; pinnules fan-shaped or obliquely elongate
............ ............ 13 Sori not marginal, borne on the undersurface of the leaf blade (if marginal, as in Pteridium and Dennstaedtia, borne on the undersurface of the leaf); petioles darkened only basally (if at all), rachis green, tan, or reddish; pinnules not notably fan-shaped or obliquely elongate.
............ ............ ..14 Outline of leaf blade narrowed to base, the widest point > 7 pinna pairs above the base, the lowermost pinnae < 1/4 as long as the longest pinnae; rhizomes long-creeping, the leaves scattered or in small tufts, forming clonal patches
............ ............ ..14 Outline of the leaf blade slightly if at all narrowed to the base, the widest point < 5 pinna pairs from the base, the lowermost pinnae > 1/2 as long as the longest pinnae; rhizomes short-creeping, the leaves clustered, not forming clonal patches (or with rhizomes long-creeping, leaves scattered, forming clonal patches in Dennstaedtia in DENNSTAEDTIACEAE).
............ ............ ....15 Rhizomes long-creeping, leaves scattered, forming clonal patches; vascular bundles in the petiole 1, U-shaped (even in the lower petiole); sori very small, marginal in sinuses, the indusium cup-like, 2-parted, the outer part a modified tooth of the leaf blade; leaf blades conspicuously puberulent with septate glandular hairs
............ ............ ....15 Rhizomes short-creeping, the leaves clustered, not forming clonal patches; vascular bundles in the petiole 2-7 (sometimes uniting to 1 in the upper petiole); sori mostly larger, mostly not marginal, the indusium not as above (though cup-like in Woodsia obtusa); leaf blades either glabrous, glabrescent, with flattened scales, or puberulent with glandular trichomes.
............ ............ ......16 Vascular bundles (3-) 5 (-7) in the petiole
............ ............ ......16 Vascular bundles 2 in the petiole (or uniting near the leaf blade into 1).
............ ............ ........17 Leaves 25-65 cm wide, with whitish, straight, acicular hairs; [species adventive and weedy]
............ ............ ........17 Leaves 5-25 (-30) cm wide, with scales and minute glands (sometimes also with septate hairs); [native species].
............ ............ ..........18 Leaves 1-pinnate-pinnatifid; indusium cup-like, attached beneath the sorus and consisting of 3-6 lanceolate to ovate segments
............ ............ ..........18 Leaves 2-pinnate-pinnatifid; indusium flap-like, pocket-like, or hood-like, attached at one side of the sorus and arching over it.
............ ............ ............ 19 Leaves 10-30 cm wide, the tip acute to acuminate; indusium flap-like
............ ............ ............ 19 Leaves 4-9 cm wide, the tip long-attenuate; indusium pocket-like or hood-like

Key A7: medium to large ‘fern-like’ pteridophytes, terrestrial, growing in soil, not associated with rock outcrops

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1 Leaf vine-like (with indeterminate growth), 0.3-10 m long, the branching dichotomous, 1 branch of each dichotomy terminating in a pair of pinnae, the pinnae often widely spaced (> 10 cm apart).
..2 Vine-like leaves scrambling or trailing; sporangia borne 6-12 per sorus
..2 Vine-like leaves twining; sporangia borne singly, each subtended by an indusium-like flap
1 Leaf not vine-like, 0.3-3 m long, the branching not as described above, the pinnae regularly and more-or-less closely spaced (mostly < 10 cm apart).
....3 Leaf blades broadly (about equilaterally) triangular, pentagonal, or flabellate in outline, 0.7-1.3× as long as wide.
......4 Leaf blades flabellate or fan-shaped in outline, the petiole branched once dichotomously, each branch bearing 3-7 pinnae on one side of the rachis only
......4 Leaf blades pentagonal or broadly triangular in outline, the petiole not branched dichotomously.
........5 Leaf blade pentagonal in outline, the terminal pinna the largest; sori either submarginal, roundish, the indusium reniform, or marginal and continuous, covered by a false indusium; [exotic, uncommonly naturalized].
..........6 Sori submarginal, roundish, the indusium reniform; leaf blade 2.4-4 dm long and wide
..........6 Sori marginal, linear, covered by a false indusium; leaf blade 10-20 dm long and wide
........5 Leaf blade broadly triangular in outline, the basal pinnae the largest; sori marginal, linear, indusium absent, the sporangia either protected by the revolute leaf margin and a minute false indusium (Pteridium), or borne in a stalked, specialized, fertile portion of the blade (Botrypus); [native, collectively common].
............ 7 Sporangia borne in a stalked, specialized, fertile portion of the blade; texture of mature blades somewhat fleshy; plants solitary from a short underground rhizome with thick, mycorrhizal roots; [primarily of moist forests]
............ 7 Sporangia borne in marginal, linear sori, indusium absent, the sporangia protected by the revolute leaf margin and a minute false indusium; texture of mature leaf blades hard and stiff; plants colonial from deep-seated rhizomes; [primarily of moist to dry woodlands and savannas]
....3 Leaves elongate in outline, mostly ovate, lanceolate, oblanceolate, or narrowly triangular, 1.5-10× or more as long as wide.
............ ..8 Leaves 2-pinnate or more divided (the pinnae divided to their midribs).
............ ....9 Leaf blade divided into sterile and fertile portions, the sterile pinnae basal, the sterile pinnules 30-70 mm long and 8-23 mm wide, serrulate, rounded basally, rounded to somewhat acute apically, the fertile pinnae terminal and greatly reduced in size, the fertile pinnules 7-11 mm long and 2-3 mm wide
............ ....9 Leaf blade not divided into sterile and fertile portions (though often not all pinnules on a leaf bearing sporangia), the sporangia-bearing pinnules only slightly if at all reduced in size, both fertile and sterile pinnules usually 4-20 mm long and 2-10 mm wide.
............ ......10 Rhizomes long-creeping, leaves scattered, forming clonal patches; vascular bundles in the petiole either 1, U-shaped (even in the lower petiole) or 3 or more; sori very small, marginal in sinuses, the indusium cup-like, 2-parted, the outer part a modified tooth of the leaf blade; leaf blades conspicuously puberulent with septate hairs or glabrous to puberulent with glandular trichomes
............ ......10 Rhizomes short-creeping, ascending, or erect, the leaves clustered, not forming clonal patches; vascular bundles in the lower petiole 2-7 (sometimes uniting to 1 in the upper petiole); sori mostly larger, mostly not marginal, the indusium not as above (though cuplike in Woodsia obtusa); leaf blades either glabrous, glabrescent, with flattened scales, or puberulent with glandular trichomes.
............ ........11 Vascular bundles (3-) 5 (-7) in the petiole
............ ........11 Vascular bundles 2 in the petiole.
............ ..........12 Undersurface of leaf with white or yellow farina (waxy exudate); [FL peninsula]
............ ..........12 Undersurface of leaf green, lacking farina; [collectively widespread]
............ ............ 13 Leaves 25-65 cm wide, with whitish, straight, acicular, septate hairs; [species adventive and weedy]
............ ............ 13 Leaves 5-25 (-50) cm wide, with scales and minute glands (sometimes also with septate hairs); [native species, widespread].
............ ............ ..14 Leaves 1-pinnate-pinnatifid; indusium cup-like, attached beneath the sorus and consisting of 3-6 lanceolate to ovate segments
............ ............ ..14 Leaves 2-pinnate-pinnatifid; indusium flap-like, pocket-like, or hood-like, attached at one side of the sorus and arching over it.
............ ............ ....15 Leaves 4-9 cm wide, the tip long-attenuate; indusium pocket-like or hood-like
............ ............ ....15 Leaves 9-30 cm wide, the tip acute to acuminate; indusium flap-like
............ ..8 Leaves 1-pinnate-pinnatifid or less divided (the pinnae entire, toothed, lobed or pinnatifid).
............ ............ ......16 Leaves 1-pinnatifid, most of the pinnae not fully divided from one another (the rachis winged by leaf tissue most or all of its length); leaves either dimorphic, the fertile much modified, stiff and/or woody (Onoclea in ONOCLEACEAE or Lorinseria in BLECHNACEAE), or not dimorphic (Pecluma in POLYPODIACEAE).
............ ............ ........17 Sporangia borne in circular sporangia on the undersurface of monomorphic leaves; [n. FL southwards]
............ ............ ........17 Sporangia borne on modified, stiff and/or woody leaves; [widespread in our area]
............ ............ ..........18 Fertile leaf stiff but herbaceous, the pinnae linear, not at all bead-like; margins of sterile pinnae finely serrulate, otherwise slightly wavy or straight; pinnae mostly with acute apices, tending to be borne alternate
............ ............ ..........18 Fertile leaf woody, with bead-like segments; margins of sterile pinnae entire, often wavy or the lowermost even somewhat lobed; pinnae mostly with obtuse apices, tending to be borne opposite
............ ............ ......16 Leaves 1-pinnate or 1-pinnate-pinnatifid, the pinnae fully divided from one another (the rachis naked for most of its length, often winged in the terminal portion); leaves dimorphic or not.
............ ............ ............ 19 Rhizomes long-creeping, leaves scattered, forming clonal patches.
............ ............ ............ ..20 Sori elongate, along either side of the main veins
............ ............ ............ ..20 Sori roundish, borne away from the main veins.
............ ............ ............ 19 Rhizomes short-creeping, the leaves clustered, not forming clonal patches (or rhizomes of both types, but leaves borne only in clusters on the short erect ones, in Matteuccia)
............ ............ ............ ....21 Plants moderately to very robust, the leaves typically 6-50 dm tall; leaves either strongly dimorphic, the fertile leaves very unlike the sterile, brown at maturity (Matteuccia and Osmundastrum cinnamomeum), or the fertile pinnae very unlike the sterile, brown at maturity, borne as an interruption in the blade, with normal green pinnae above and below (Osmunda claytoniana), or the fertile pinnae toward the tip of the leaf and with sporangia entirely covering the lower surface (Acrostichum); rachises scale-less, petioles scale-less (except at the base in Matteuccia).
............ ............ ............ ......22 Leaves 1.5-5 m long; fertile pinnae with sporangia covering the lower surface; [n. FL southward]
............ ............ ............ ......22 Leaves 0.6-2.5 m long; fertile portions otherwise.
............ ............ ............ ........23 Leaves strongly tapering to the base from the broadest point (well beyond the midpoint of the blade), the basal-most pinnae much < ½ as long as the largest pinnae
............ ............ ............ ........23 Leaves slightly if at all tapering to the base, about equally broad through much of their length, the basal-most pinnae much > ½ as long as the largest pinnae
............ ............ ............ ....21 Plants mostly less robust, the leaves 3-10 dm tall (except Dryopteris ludoviciana, D. celsa, D. goldiana, and Nephrolepis exaltata to 15 dm); leaves not at all or only slightly dimorphic, the fertile differing in various ways, such as having narrower pinnae (as in Dryopteris ludoviciana, Polystichum acrostichoides, Diplazium, Deparia, and Thelypteris palustris) or the fertile leaves taller and more deciduous (as in Asplenium platyneuron and Dryopteris cristata), but not as described in the first lead; rachises and petioles variously scaly or scale-less, but at least the petiole and often also the rachis scaly if the plants over 1 m tall.
............ ............ ............ ..........24 Sori elongate, the indusium elongate, attached along one side as a flap.
............ ............ ............ ............ 25 Petiole and rachis lustrous brownish-black; fertile leaves 2-8 (-12) cm wide
............ ............ ............ ............ 25 Petiole and rachis green; fertile leaves 10-20 (-30) cm wide.
............ ............ ............ ............ ..26 Leaves 1-pinnate-pinnatifid (the pinnae pinnatifid)
............ ............ ............ ..........24 Sori roundish, the indusium kidney-shaped or roundish, attached by a central stalk.
............ ............ ............ ............ ....27 Leaves 1-pinnate, the pinnae toothed and each with a slight to prominent lobe near the base on the side toward the leaf tip (except Nephrolepis exaltata in NEPHROLEPIDACEAE); indusium peltate (Polystichum in DRYOPTERIDACEAE) or reniform or crescent-shaped (Nephrolepis in NEPHROLEPIDACEAE).
............ ............ ............ ............ ......28 Leaves pale green, thin in texture; pinnae articulate to rachis, deciduous with age; thin, rhizome bearing elongate, thin, wiry stolons; [mostly, if not entirely, exotic in our area, rare]
............ ............ ............ ............ ......28 Leaves dark-green, subcoriaceous to coriaceous; pinnae neither articulate nor deciduous with age; rhizome not producing stolons; [native, common]
............ ............ ............ ............ ....27 Leaves 1-pinnate-pinnatifid, the pinnae pinnatifid, generally lacking a prominent basal lobe; indusium reniform.
............ ............ ............ ............ ........29 Vascular bundles in the petiole 2, uniting above
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