1 Plants in flower.

  2 Petals pink to purple.

    3 Flowers > 25 mm across (individual petals > 15 mm long)

    3 Flowers < 20 mm across (individual petals < 12 mm long).

      4 Leaves flattened in cross-section, > 2.5 mm wide, elliptic.

      4 Leaves terete to hemispherical in cross-section, usually < 2 mm wide, linear to lanceolate.

        5 Petals not bilobed; stamens usually < 30; [collectively widespread and of various habitats].

          6 Petals dark pink to purple; seeds 0.4- 0.6 mm wide, round; leaves narrowly elliptic, 3-5× as long as wide

          6 Petals medium to pale pink; seeds 0.7-0.9 mm wide, elongate; leaves linear, ca. 8× as long as wide

  2 Petals yellow, orange, copper, bronze, or white.

             7 Flowers > 25 mm across (individual petals > 15 mm long).

               8 Leaves terete; capsule not encircled by an expanded, membranaceous wing

               8 Leaves flat; capsule encircled by an expanded, membranaceous wing

                 9 Petals yellow, tipped with copper or red; [MS and AR westwards]

                 9 Petals variable in color; [exotic, in disturbed situations or naturalized on granite flatrocks in SC and GA]

             7 Flowers < 20 mm across (individual petals < 12 mm long).

                   10 Leaf blades terete or hemispheric in cross-section, linear, usually < 3 mm wide.

                     11 Stem nodes and inflorescences with conspicuous trichomes; flowers < 8 mm in diameter; [TX, waif elsewhere]

                     11 Stem nodes and inflorescences with inconspicuous trichomes; flowers > 9 mm in diameter; [s. FL]

                   10 Leaf blades flattened in cross-section, obovate or spathulate, 2-15 mm wide.

                       12 Capsule encircled by an expanded membranaceous wing; [of granitic and sandstone outcrops in SC and GA]

                       12 Capsule not encircled by an expanded membranaceous wing; [collectively widespread in our area, and of various habitats].

                          13 Leaves opposite; petals 4 (-5); tap-rooted perennial; [narrowly restricted to limestone outcrops in pine rocklands in the Florida Keys, and southeastwards in the Bahamas]

                          13 Leaves alternate to subopposite; petals 5; fibrous-rooted annuals; [widely distributed in various habitats].

                            14 Epidermal cells of the seed coat (stellulae) with broad lobes, the lobes almost never longer than broad; seeds bluish (covered by wax); seeds retained in the nipple-like projection of the operculum avg. 4; [not readily identifiable by characters other than those of mature capsules and seeds]

                            14 Epidermal cells of the seed coat (stellulae), with narrow lobes, the lobes mostly distinctly longer than broad (and sometimes developing prominent papillae at their ends); seeds not bluish (not covered by wax); seeds retained in the nipple-like projection of the operculum avg. 1-3; [not readily identifiable by characters other than those of mature capsules and seeds]

1 Plants in fruit.

                              15 Capsule encircled by an expanded membranaceous wing.

                                16 [Native in our area, in thin soil on granitic and sandstone outcrops in SC and GA]

                                16 [Introduced cultivar, persistent to weakly spreading from plantings]

                                  17 Petals yellow, tipped with copper or red; [MS and AR westwards]

                                  17 Petals variable in color; [exotic, in disturbed situations or naturalized on granite flatrocks in SC and GA]

                              15 Capsule not encircled by an expanded membranaceous wing.

                                    18 Leaves flattened in cross-section, > 2.5 mm wide, obovate to spatulate.

                                       19 Trichomes at nodes conspicuous; seeds round, < 0.6 mm long; leaves elliptic, with an acute to acuminate apex

                                       19 Trichomes at nodes inconspicuous; seeds elongate, > 0.4 mm long; leaves spatulate, with a rounded apex

                                         20 Capsules ca. 2 mm wide; styles 3; seeds ca. 0.5 mm long; leaves opposite; [narrowly restricted to limestone outcrops in pine rocklands in the Florida Keys, and southeastwards in the Bahamas]

                                         20 Capsules 4-9 mm wide; styles 3-6; seeds 0.7-1 mm long; leaves alternate to subopposite; [widely distributed in various habitats].

                                           21 Epidermal cells of the seed coat (stellulae) with broad lobes, the lobes almost never longer than broad; seeds bluish (covered by wax); seeds retained in the nipple-like projection of the operculum avg. 4

                                           21 Epidermal cells of the seed coat (stellulae), with narrow lobes, the lobes mostly distinctly longer than broad (and sometimes developing prominent papillae at their ends); seeds not bluish (not covered by wax); seeds retained in the nipple-like projection of the operculum avg. 1-3

                                    18 Leaves terete to hemispherical in cross-section, usually < 3 mm wide, linear to lanceolate.

                                             22 Nodes and inflorescences with inconspicuous trichomes.

                                               23 Seeds < 0.7 mm in diameter; epidermal cells of the seed coat (stellulae) obscurely stellate, and without tubercles

                                             22 Nodes and inflorescences with conspicuous trichomes.

                                                 24 Seeds > 0.65 mm wide.

                                                    25 Longest leaves mostly > 20 mm long; capsules mostly > 4 mm in diameter; [introduced, usually in obviously disturbed sites]

                                                    25 Longest leaves mostly < 17 mm long; capsules mostly < 3.5 mm in diameter; [native, on granitic or diabase flatrocks]

                                                 24 Seeds < 0.65 mm wide

                                                      26 Capsules 1.1-2.0 mm in diameter; seeds 0.3-0.5 mm in diameter

                                                      26 Capsules 1.5-5 mm in diameter; seeds (0.4-) 0.5-0.6 mm in diameter