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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 |