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Key to Osmundaceae
https://fsus.ncbg.unc.edu/main.php?pg=show-key.php&keyid=39385
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] | |
Key A7: medium to large ‘fern-like’ pteridophytes, terrestrial, growing in soil, not associated with rock outcrops
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https://fsus.ncbg.unc.edu/main.php?pg=show-key.php&keyid=40698
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). | |
![]() Show caption*© Alan Cressler: Dicranopteris flexuosa, Deep Creek Preserve, Volusia County, Florida 4 by Alan Cressler ![]() Show caption*© Alan Cressler: Dicranopteris flexuosa, Deep Creek Preserve, Volusia County, Florida 3 by Alan Cressler | |
![]() Show caption*© Alan Cressler: Lygodium microphyllum, Highway 66, Hardee County, Florida 4 by Alan Cressler | |
3 Leaf blades broadly (about equilaterally) triangular, pentagonal, or flabellate in outline, 0.7-1.3× as long as wide. | |
![]() Show caption*© Alan Cressler: Adiantum pedatum, Left Fork, Great West Canyon, The Subway Hike, Zion National Park, Washington County, Utah 1 by Alan Cressler | |
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]. | |
![]() Show caption*© Alan Cressler: Pteridium pseudocaudatum, Lodge Bog, Easter Plantation, Brooks County, Georgia 1 by Alan Cressler | |
3 Leaves elongate in outline, mostly ovate, lanceolate, oblanceolate, or narrowly triangular, 1.5-10× or more as long as wide. | |
![]() Show caption*© Alan Cressler: Osmunda spectabilis, Sporangia, Big Creek Swamp, Hilochee Wildlife Management Area, Lake County, Florida 2 by Alan Cressler 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. | |
![]() Show caption*© Alan Cressler: Macrothelypteris torresiana (left), Dennstaedtia bipinnata (right), Seminole County, Florida 1 by Alan Cressler | |
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). | |
![]() Show caption*© Alan Cressler: Pecluma dispersa, Panasoffkee Outlet River, Chert Ledges, Sumter County, Florida 3 by Alan Cressler | |
19 Rhizomes long-creeping, leaves scattered, forming clonal patches. | |
![]() Show caption*© Alan Cressler: Macrothelypteris torresiana, Gola Creek, Pike County, Georgia 4 by Alan Cressler ![]() Show caption*© Alan Cressler: Thelypteris palustris var. pubescens, Hurricane Creek Outlet Bog, Upper Nantahala River, Nantahala National Forest, Macon County, North Carolina 3 by Alan Cressler | |
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). | |
![]() Show caption*© Alan Cressler: Acrostichum danaeifolium, Allapatchee Park, Alligator Creek, Punta Gorda, Charlotte County, Florida 2 by Alan Cressler | |
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. | |
![]() Show caption*© Alan Cressler: Asplenium trichomanes, Cohutta Wilderness, Chattahoochee National Forest, Fannin County, Georgia 2 by Alan Cressler | |
![]() Show caption*© Alan Cressler: Polystichum munitum, Rain Forest Resort Village, Quinault Rain Forest, Grays Harbor County, Washington 1 by Alan Cressler | |
27 Leaves 1-pinnate-pinnatifid, the pinnae pinnatifid, generally lacking a prominent basal lobe; indusium reniform. | |