1 Flowers solitary, on terminal or axillary pedicel 0-50 (-70) mm long; corolla salverform; leaves 2-15 (-20) mm long.

  2 Stems prostrate and creeping, rooting at the node.

    3 Corolla blue (rarely white); capsule 2.5-5.0 mm across; leaves 0.5-7 mm wide; pedicel single or paired, to 60 mm long; flowers all chasmogamous and aerial; [of the Mountains]

  2 Stems erect or spreading to prostrate, not rooting at node (even if prostrate).

      4 Flowers borne in leaf axil; pedicel either straight or recurving in fruit; annuals with a long, thin, sparingly branched taproot; [TX, AR, OK westwards and southwards].

        5 Corolla 5-8 mm long; stipule to 2.5 mm long, bearing bristle at the margin; flowers heterostylous

        5 Corolla 1-3 mm long; stipule < 0.5 mm long, lacking marginal bristle; flowers homostylous.

          6 Corolla 1-2 mm long, about as long as the calyx; capsule erect, glabrous

          6 Corolla 2-3 mm long, longer than the calyx; capsule recurved, short-hairy (hirtellous).

             7 Cauline leaves (the larger) > 1 mm wide; pedicel 0-2 mm long; capsule 1/4 to 1/2 inferior

             7 Cauline leaves < 1 mm wide; pedicel 3-8 mm long; capsule about 3/4s inferior

      4 Flowers borne terminally on the stem; pedicel remaining straight in fruit, thus the capsule borne upright; annuals or perennials with fibrous and branched root; [collectively widespread in our region].

               8 Stems 1-4 (-7) cm tall; leaves mostly oblanceolate, 0.3-3.0 mm wide; corolla 5-12 mm long, white to pale pink; seeds with a hilar ridge in an elliptical depression

               8 Stems 1-26 cm tall; leaves elliptic, ovate or spatulate, 0.3-9.0 mm wide (at least some on a plant generally > 3 mm wide); corolla 2-21 mm long, purple, pale blue, pink, or white; seeds subglobose with a ventral cavity.

                 9 Plants perennial, with a well-developed, persistent basal rosette; corolla 5.8-16 (-21) mm long, the tube (2-) 4-11 (-12) mm long

                 9 Plants annual, with at most a few short-lived basal leaves; corolla 2-10 (-12) mm long, the tube 0.8-5.5 mm long.

                   10 Calyx lobe slightly shorter than to slightly longer than the corolla tube; corolla white, 2.0-5.5 mm long, the tube 0.8-2.5 mm long

                   10 Calyx lobe 1/5 as long as to slightly longer than the corolla tube; corolla purple or violet (rarely white), 3.5-10 (-12.5) mm long, the tube 2.0-5.5 mm long

1 Flowers several to many, in terminal cyme; corolla funnelform; leaves (8-) 10-60 mm long.

                     11 Stipule of mid-cauline leaves ciliate or fringed, and also often bristle-tipped; largest mid-cauline leaves 0.5-3 mm wide; capsule either obovoid-cylindric, longer than wide, the free calyx lobe distinctly shorter than the capsule, or (in var. floridana) globose or subglobose; [of calcareous glades and barren or in FL of calcareous sands]

                       12 Capsule globose or subglobose, 1-1.3× as long as wide; largest leaves 0.3-1.2 mm wide; [of pine rocklands in s. FL]

                       12 Capsule turbinate, oblong, or ellipsoid, 1.3-2.2× as long as wide; largest leaves 0.5-6 mm wide; [widespread in our area, and in various habitats]

                          13 Largest mid-cauline leaves 3-6 mm wide; main stem leaves lacking axillary shoot leaf fascicle; inflorescence loose, usually with 5-10 pure white flowers per square cm in pressed specimens; corolla pure white; [of limestone palisade cliff of KY and TN]

                          13 Largest mid-cauline leaves 0.5-3 mm wide; main stem leaves with axillary shoot leaf fascicle; inflorescence loose, usually with 10-20 flowers per square cm in pressed specimens; corolla pale blue; [collectively widespread in our area]

                            14 Calyx, upper stems, and leaves papillose with elongated, hair-like papillae; [s. TX]

                            14 Calyx, upper stems, and leaves glabrous or ciliate along margin; [collectively widespread, including s. TX].

                              15 Stem internode 2-10 (-20) mm long; plants branched at and near the base, the branches sprawling or decumbent, mat-forming; [of FL dune and beaches]

                              15 Stem internode 6-46 mm long; plants branched less prolifically, if branched at or near the base, the branches ascending or vertical; [widespread in our area, usually on rocky, calcareous substrates]

                     11 Capsule as long as wide or wider, depressed globose, the free calyx lobe about as long as the capsule; stipule of mid-cauline leaves not ciliate, fringed, or bristle-tipped; leaves 0.5-34 mm wide; [of various habitats, including calcareous glades and barren]

                                16 Basal leaves persistent in a rosette until and past flowering; leaves distinctly ciliate

                                16 Basal leaves absent at the onset of flowering; leaves smooth-margined or ciliate.

                                  17 Leaves ovate or lanceolate, 1-6× as long as wide, 4-34 mm wide, widest toward the base or at the middle; calyx lobe 1-7 mm long.

                                    18 Calyx lobe 4-7 mm long; leaves mostly lanceolate (varying from narrowly lanceolate to broadly ovate), 17-33 mm long, 4-10 mm wide, 3.3-6× as long as wide

                                    18 Calyx lobe 1-4 mm long; leaves mostly ovate (varying from broadly ovate to ovate-lanceolate), 8-63 mm long, 6-34 mm wide, 1-3.2× as long as wide.

                                       19 Corolla light purple to white, (4-) 5-8 (-10) mm long; leaves (10-) 25-50 (-60) mm long, (6-) 12-30 (-34) mm wide; stems sparsely to densely pubescent; median internode 2-9 cm long; leaves with pubescence ciliate on the leaf margin, on the midrib, and scattered on the surface; [of various habitats, widely distributed]

                                       19 Corolla deep purple, 8-12 mm long; leaves 8-20 (-30) mm long, 3-8 (-13) mm wide; stems glabrous (or slightly short-pubescent on the lower node only); median internode 0.5-4 cm long; leaves entirely glabrous or with pubescence ciliate on the leaf margin, on the midrib, but lacking from the leaf surface; [of high elevation rocky summits and adjacent grassy bald in w. NC, e. TN, and sw. VA]

                                  17 Leaves linear to narrowly elliptic, 4-20× as long as wide, 0.5-6 mm wide, widest at the middle or near the apex or nearly equally wide for most of their lengths; calyx lobe 0.5-3 mm long.

                                         20 Corolla lobe densely pilose within, the hair 0.5-1.2 (-1.8) mm long; cauline leaves 0.3-2.0 (-3.5) mm wide; stems glabrous; [of AR and OK]

                                         20 Corolla lobe glabrous within, or, if pubescent, with hair < 0.5 mm long; cauline leaves 0.5-8.0 mm wide; stems glabrous or puberulent; [widespread in our area].

                                           21 Leaves 1.3-4.7 cm long, 0.5-4.0 mm wide (mostly < 2.5 mm wide), 7-20× as long as wide; inflorescence very diffuse and open, to 20 cm long, the branches ascending, spreading, or deflexed, slender and often ultimately filiform, with 1-4 remote node bearing reduced leaves, the pedicel to 14 mm long; internode mostly 4-9; mature capsule mostly 1.5-2.5 mm long and wide; stem densely cinereous-puberulent, especially at the node

                                           21 Leaves 1.6-4.0 cm long, 1.5-6.0 mm wide (mostly > 2.5 mm wide), 4-11× as long as wide; inflorescence rather open to rather compact, < 12 cm long, the branches ascending or spreading, slender, pedicel to 8 mm long; internode mostly 7-11; mature capsule mostly 1.8-3.0 mm long and wide; stem densely cinereous-puberulent, glabrate, or glabrous.

                                             22 Internode 4-7; stipule of median node ovate, to 3.3 mm long, to 3.5 mm wide, the apex often rounded; [northern, reaching our area in n. NJ]

                                             22 Internode (6-) 7-11 (-13); stipule of median node lanceolate or deltoid, to 3 mm long, to 2.5 mm wide, the apex usually acute to acuminate; [collectively widespread].

                                               23 Stems glabrous or glabrate (sometimes puberulent on the node only); internode 7-10, the median internode (1.1-) 2.0-4.5 (-6.0) cm long; [of seasonally wet soil mats on moderate to high elevation granitic domes in sw. NC, nw. SC, and ne. GA]

                                               23 Stems densely cinereous-puberulent; internode (6-) 7-11 (-13), the median internode (1.0-) 1.5-3.5 (-4.4) cm long; [of dry sandy, shaley, gravelly, or rocky soil, widely distributed]