1 Inflorescence a spike or panicle of spikes; plants from corms; flowers slightly zygomorphic.

  2 Stem usually branched, the inflorescence appearing paniculate; tepals orange to red

  2 Stem unbranched, the inflorescence a spike; tepals any of a wide range of colors (including orange and red)

    3 Inflorescence bent at its base, the inflorescence axis more-or-less horizontal, the flowers facing upward

    3 Inflorescence erect, the flowers facing outward

1 Inflorescence an umbellate 1-sided cyme; plants from rhizomes or bulbs; flowers actinomorphic.

      4 Leaves planar; plants from rhizomes (or indistinct) or a bulb (in Iris xiphium).

        5 Style branches broad, petaloid, terminating in paired crests

        5 Style branches not broad or petaloid.

          6 Tepals 6-15 mm long, blue, purple, lavender, pink, magenta, white, or yellowish-white; seeds 0.6-1.3 mm in diameter

      4 Leaves plicate; plants from bulbs.

             7 Tepals unequal, the inner whorl < ½ as long as the outer whorl

             7 Tepals nearly equal in length.

               8 Style recurved, with 3 flat branches that are < 2 mm long

               8 Style straight, each of the 3 branches further divided into slender lobes

                 9 Style branches divided for ca. ½ their length; style arms arching over or between the anthers; tepals dark purple

                 9 Style branches divided nearly to base; style arms extending horizontally between the anthers; tepals blue, white in the center

1 Plant from an ovoid bulb; [subgenus Xiphium; or genus Xiphion]

1 Plant from short to elongate rhizomes.

  2 Style branches broad, petaloid, terminating in paired crests; seeds tan to brown, in a capsule.

    3 Sepal "signal" (see above) of multicellular hairs (the “beard”), along the midrib of the claw and the base of the blade; [subgenus Iris; or genus Iris].

      4 Aboveground stem <1 cm tall; floral tubes 6-10 cm long

      4 Aboveground stem 60-120 cm tall; floral tubes 1-2.5 cm long

        5 Spathes scarious, silvery-white; corollas pale blue or pale lilac

        5 Spathes green (or purplish) and herbaceous, with scarious margins; corollas white, blue-violet, or purple.

          6 Corollas white (with yellow or greenish tint near the base); inflorescences simple or slightly branched, the branches hidden with the bracts at anthesis

          6 Corollas blue-violet or purple (very rarely whitish, and then with violet tint near the base; inflorescences visibly branched, the terminal branches extending beyond the bracts at anthesis

    3 Sepal "signal" consisting of contrasting color, ridges, small unicellular hairs, and/or a cockscomb-like crest.

             7 Rhizome branches cord-like, with scale-like leaves, enlarging at the apex to produce vegetative leaves, additional branches, and flowering stems.

               8 Stems 30-80 cm tall; leaves 30-60 cm long, 0.2-0.7 cm wide; cordlike portions of rhizomes to 4 dm long; [of wetlands]; [section Limniris, series Prismaticae; or genus Limniris]

               8 Stems 2-15 cm tall; leaves 10-45 cm long, 0.3-2.5 cm wide; cordlike portions of rhizomes to 2 dm long; [of dry to mesic uplands].

                 9 Sepal "signal" a 3-ridged, toothed crest; leaves 10-25 mm wide, green, falcate; flowers not or only slightly fragrant; rhizomes surficial (one can "pull" them off the ground by gently tugging on the leaves); [generally of mesic and fertile soils]; [section Lophiris; or genus Lophiris]

                 9 Sepal "signal" merely a primarily orange color patch (not a crest); leaves 3-13 mm wide, blue-green, straight or nearly so; flowers strongly fragrant; rhizomes deeply buried (not easily "pulled"); [generally of dry and acid soils]; [section Limniris, series Vernae; or genus Gattenhofia].

                   10 Leaf-bearing offshoots spaced at 0.2-3 cm along the rhizome, thus forming tight to loose clumps of 2 or more leafy, above-ground shoots; rhizomes 2.5-8 mm in diameter, typically irregular, knotty, and contorted, scales not obvious; leaves 5-13 mm wide, with 15-29 veins, usually medium to dark green; leaves typically borne angled to the ground and further arching; capsules 1.7-3.2 cm long; [in and west of the w. Piedmont and Appalachians and extending to the Gulf Coastal Plain in GA, FL, AL, and MS]

                   10 Leaf-bearing shoots spaced at intervals of (5-) 8-15 cm along the rhizome, thus forming colonies with well-spaced, individual, leafy above-ground shoots; rhizomes 1-2.5 mm in diameter, bearing obvious and well-spaced scales; leaves 3-8 mm wide, with 9-19 veins, usually pale or glaucous green; leaves borne rigidly vertical, at 90 degrees to the ground; capsules 1.2-1.8 cm long; [of the Coastal Plain and e. Piedmont, from e. VA to e. GA]

             7 Rhizome branches like the primary rhizome, not as above.

                     11 Petals 1-2 cm long; [section Limniris; series Tripetalae; or genus Limniris]

                     11 Petals 2-9.5 cm long.

                       12 Stems hollow; [section Limniris; series Sibirica; or genus Limniris].

                          13 Spathes herbaceous at flowering time; capsule 3.5-5.5 cm long

                          13 Spathes scarious at flowering time; capsule 2-3.5 cm long

                       12 Stems solid.

                            14 Capsules 3-angled or nearly round in cross-section; [section Limniris; series Laevigatae; or genus Limniris].

                              15 Perianth yellow

                              15 Perianth blue-violet (rarely white).

                                16 Flowers 8-15 cm in diameter; leaves 0.5-1.5 cm wide; [exotic, cultivated, rarely escaped]

                                16 Flowers 6-8 cm in diameter; leaves 1-4 cm wide; [native].

                                  17 "Signal" a greenish-yellow, papillate patch, surrounded by an area of heavily veined purple-on-white; [of VA northward]

                                  17 "Signal" a bright yellow, pubescent patch.

                                    18 Plants to 10 dm tall, usually with 1-2 well-developed branches; capsule 7-11 cm long

                                    18 Plants to 6 dm tall, little or not at all branched; capsule 4-7 cm long

                            14 Capsules 6-angled or ridged in cross-section; [section Limniris, series Hexagonae; or genus Phaeiris].

                                       19 Perianth dull copper or orange-brown (or dark yellow) (fading in nature or drying in the herbarium to a bluish or purplish color); petals spreading or declining

                                       19 Perianth blue-violet (rarely white); petals erect to spreading.

                                         20 Stems declining or semi-erect, sharply zigzag

                                         20 Stems erect, slightly if at all zigzag.

                                           21 Capsules 2.5-3.5 cm long, hexagonal in cross-section, 3 sides flat, the alternating sides with 2 rounded ridges separated by a shallow groove

                                           21 Capsules 6-10 cm long (3.5-7 cm in I. rivularis), slightly to strongly hexagonal in cross-section.

                                             22 Capsules with 6 broad rounded lobes, indehiscent.

                                               23 Capsules 3.5-7 cm long; sepals ca. 9 cm long; flowers slightly fragrant; [endemic to St. Marys River in se. GA and ne. FL]

                                               23 Capsules (6.5-)8-10 cm long; sepals 9.5-11.5 cm long; flowers strongly musk-scented [FL panhandle w. to e. TX]

                                             22 Capsules with 6 sharp or winglike ridges, dehiscent.

                                                 24 Capsule ridges sharp

                                                 24 Capsule ridges winged