1 Sterile portion of the leaf simple, unlobed or palmately few-lobed; veins anastamosing; fertile stalks unbranched, the sporangia embedded in a linear spike; [subfamily Ophioglossoideae].

  2 Plants epiphytic; sterile leaf blades either simple, or once-dichotomously lobed, or palmately lobed, to 30 cm wide; main areoles of anastamosing veins mostly > 30 mm long; [of peninsular FL]

    3 Sterile blade palmately lobed with 2-11 lobes, the blade usually wider than long or nearly so; fertile portion of blade (1-) 2-15 per leaf

    3 Sterile blade strap-shaped, entire or rarely once or twice dichotomously lobed, the blade much longer than wide; fertile portion of blade 1 per leaf

  2 Plants terrestrial; sterile leaf blades unlobed, to 5 cm wide; main areoles of anastamosing veins mostly < 6 mm long; [collectively widespread]

1 Sterile leaf blade pinnatifid, pinnate, or more divided; veins free; fertile stalks branched, the sporangia sessile or stalked; [subfamily Botrychioideae].

      4 Fertile stalk joined to the stalk of the sterile leaf blade near the rhizome, far below the base of the leaf blade, and usually at or below the surface of the ground; leaves evergreen, appearing in spring, summer, or fall, and withering the following spring; sterile leaf blades triangular (or pentagonal) in general outline

      4 Fertile stalk joined to the stalk of the sterile leaf blade near the base of the leaf blade, far above the rhizome, and usually well above the surface of the ground; leaves deciduous, appearing in spring and withering the same summer or fall; sterile leaf blades either triangular (or pentagonal) or elongate in general outline.

        5 Sterile leaf blade 3-ternate or even more finely divided; plants (9-) 30-50 cm tall; sterile blade herbaceous in texture, 10-40 cm long

1 Leaf blades appearing to be digitate (the segments arising at a single point); [FL peninsula]

1 Leaf blades pinnate or pinnatifid (in various degrees); [collectively widespread]

  2 Petiole branched once dichotomously, each branch then bearing 3-7 pinnae on the same side of the 2 rachis branches, the overall outline of the blade in the shape of a fan and often broader than long

  2 Petiole not branched dichotomously, the outline of the blade either longer than broad or triangular and about as wide as long.

    3 Leaves pinnatifid or bipinnatifid, most of the pinnae not fully divided from one another (the rachis winged by leaf tissue most or all of its length).

      4 Sporangia borne on an erect stalk that arises at or above ground level from the petiole of the sterile leaf blade (joining the petiole of the sterile leaf above the rhizome)

      4 Sporangia either borne on normal leaf blades or on specialized (fertile) leaves separate from the rhizome.

        5 Leaves monomorphic, the sori borne on normal leaf blades

        5 Leaves dimorphic, the sori borne on leaves significantly different from normal leaves.

          6 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 oppositely

          6 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 alternately

    3 Leaves pinnate, pinnate-pinnatifid, 2-pinnate, or even more divided (the rachis naked for most of its length, often winged in the apical portion).

             7 Leaves broadly triangular in outline, about as broad as long.

               8 Sporangia borne on normal leaf blades

               8 Sporangia borne on an erect stalk that arises at or above ground level from the petiole of the sterile leaf blade (joining the petiole of the sterile leaf above the rhizome)

             7 Leaves lanceolate in outline, definitely longer than broad; sporangia either borne on normal leaf blades, or on slightly dimorphic blades, or on the basalmost pinnae of the leaf, or on an erect stalk that arises at or above ground level from the petiole of the sterile leaf blade (joining the petiole of the sterile leaf above the rhizome).

                 9 Leaf blades 10-30 (-100) cm long; sporangia either borne on normal leaf blades, or on slightly dimorphic blades, or on basalmost pinnae of the leaf.

                   10 Leaves dark green, subcoriaceous in texture, evergreen

                   10 Leaves light to medium green, herbaceous in texture, deciduous to semi-evergreen.

                     11 Sori continuous along the midrib of the pinna.

                     11 Sori distinct.

                       12 Sori elongate; leaf blades somewhat dimorphic, the fertile larger and erect, the sterile smaller and prostrate, the larger leaf blades 2-4 (-6.5) cm wide; petiole with 2 vascular bundles, uniting upwards into 1 ×-shaped bundle

                       12 Sori round; leaf blades monomorphic (or slightly dimorphic in Cystopteris); the larger leaf blades 5-15 cm wide; petiole with 2 vascular bundles, uniting upwards into 1 U-shaped or V-shaped bundle.

                          13 Leaf vestiture nearly lacking (if present, not of unicellular acicular hairs or gland-tipped hairs)

                          13 Leaf vestiture of unicellular acicular hairs 0.2-1 mm long intermixed with short-stalked or sessile yellowish glands