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1 Leaves bipinnate, each pinna fully divided into distinct pinnules, the larger pinnules 3-7 cm long and 0.7-2.0 cm wide; spores borne on modified pinnae in the terminal portion of the leaf blade; veins of each pinnule 2× Y-forked (thus each vein reaching the margin as 4 final veinlets), each final veinlet making a fine tooth, thus the pinnule margins finely serrulate | |
1 Leaves pinnate-pinnatifid, each pinna additionally pinnatifid but not divided into distinct pinnules; spores borne either on specialized leaves that are normally wholly fertile (lacking flat, blade-like sterile pinnae), or hemidimorphic (juvenile leaves with only sterile pinnae, adult leaves with both sterile and fertile pinnae, the fertile pinnae borne in the middle of the leaf with sterile pinnae above and below; photosynthetic (sterile) pinnae lacking tufts of hairs; veins of each pinna lobe 1× Y-forked (thus each vein reaching the margin as 2 final veinlets), the final veinlets not creating a tooth, thus the pinna lobes entire to obscurely crenulate. | |
2 Plants with hemidimorphic leaves (juvenile leaves with only sterile pinnae; adult leaves with both sterile and fertile pinnae, the fertile pinnae borne in the middle of the leaf with sterile pinnae above and below); photosynthetic (sterile) pinnae lacking tufts of hair on the lower side of the junction of the pinna and the rachis; [usually upland] | |
2 Plants with dimorphic leaves (each leaf normally either completely photosynthetic or completely fertile); photosynthetic (sterile) pinnae with tufts of crinkly, reddish hairs near the junction with the rachis; [usually of wetlands, or in mesic soils, or drier soils with seasonal and subterranean seepage] | |
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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). | |
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 | |
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]. | |
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]. | |
3 Leaves elongate in outline, mostly ovate, lanceolate, oblanceolate, or narrowly triangular, 1.5-10× or more as long as wide. | |
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 | |
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. | |
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. | |
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] | |
19 Rhizomes long-creeping, leaves scattered, forming clonal patches. | |
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). | |
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. | |
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. | |