1 Disk flowers with 4 corolla lobes and 4 anthers; ray flowers usually apically 3-lobed.

  2 Leaves pinnately or bipinnately lobed into linear segments or narrowly lanceolate segments (sometimes plants with a mix of 1-pinnate and simple leaves as in C. leavenworthii); cypselae either wingless or with conspicuous, entire wings; [section Calliopsis].

    3 Cauline leaves usually 1-pinnate or simple; rays yellow throughout (rarely with red-brown blotches); pappi of 2 subulate scales; [s. AL and s. GA s. through peninsular FL]

    3 Cauline leaves usually 1-2+ pinnate; rays with basal red-brown blotches; pappus lacking or of 1-2 scales; [either widespread or endemic to s. TX].

      4 Plants typically 30-100 cm tall, sparsely branched from the bases; cypselae with or without wings; pappi 0.1-0.2 mm long; [widespread]

      4 Plants typically 10-30 cm tall, usually branched from the bases; cypselae 2-3 mm long, bearing conspicuous wings; pappi 0.2-1 mm long; [s. TX and n. MX]

  2 Leaves simple or with 1-2 auriculate lobes at the base, but lacking linear or pinnate segments; [section Eublepharis].

        5 All of the major cauline leaves opposite (except in C. linifolia the lowermost few leaves may be alternate).

          6 Ray flowers pink to white colored; plants rhizomatous

          6 Ray flowers yellow; plants fibrous-rooted.

             7 Leaf blades ovate (to elliptical), very gradually reduced upward, margins ciliolate, surfaces lacking tiny dark dots; achenes about 5 mm long; [se. SC south to Panhandle FL]

             7 Leaf blades linear-oblanceolate to linear, rapidly reduced upward, margins glabrous, surfaces with numerous tiny dark dots (easiest to see on undersurface); achenes < 2.5 mm long; [se. VA south to ne. and Panhandle FL, west to e. TX]

        5 All of the major cauline leaves alternate.

               8 Ray flowers pink; leaves juncoid (linear-terete)

               8 Ray flowers yellow; leaves with an expanded blade.

                 9 Outer phyllaries deltoid and very short, less than 0.3× as long as the inner phyllaries; flowering late Sep-Jan; [endemic to FL]

                 9 Outer phyllaries lanceolate, 0.4-0.8× as long as the inner phyllaries; flowering early May-early Nov; [collectively widespread].

                   10 Basal/lower leaves (at least 4 nodes) absent at anthesis; mid-cauline leaves linear to linear-lanceolate, or broadly to narrowly elliptical; achene awns 0.2-1.0 mm long; flowering Sep-Oct; [swamp forests and streamside openings, fresh-tidal creek margins; or wet calcareous savannas]; [from se. NC south to n. FL].

                     11 Leaves 8-15+ cm long, 2-7 mm wide, the blades linear to linear-oblanceolate, 20-50× as long as wide; achene awns 0.2-0.4 mm long

                     11 Leaves 4-15 cm long, 10-45 mm wide, the blades broadly to narrowly elliptical, 5-15× as long as wide; achene awns 0.7-1.0 mm long

                   10 Basal/lower leaves present at anthesis; leaves rapidly reduced upward such that mid-cauline leaves are narrow or slender; achene awns 0.5-1.5 mm long; flowering early May-early Nov; [wet savannas, seepage slopes, pitcher-plant bogs, streamhead ecotones, pocosin ecotones]; [collectively more widespread].

                       12 Leaves (at least one major leaf per plant) with 1-few slender lobes near the base (rarely no lobed leaves present or at least readily visible); achene wing broad, > 3/4 the width of the achene body; achene awns averaging 0.5 mm; leaf texture firm but not thick and leathery; flowering early May-early Jul; [se. VA south to e. GA]

                       12 Leaves without basal lobes; achene wing narrow, < ½ the width of the achene body; achene awns averaging 1.5 mm long; leaf texture thick and leathery; flowering mid Aug-early Nov; [se. NC south to c. FL and west to s. MS; also rarely inland in GA, NC, SC, off the Coastal Plain]

1 Disk flowers with 5 corolla lobes and 5 anthers; ray flowers apically entire, or with (2-) 4-5 teeth.

                          13 All of the leaves simple or the plant with a mixture of simple leaves and leaves with 1-2 (-4) basal auricles or leaflets, these distinctly smaller than the terminal lobe or leaflet.

                            14 Leaves all simple, 4-12 cm wide, the margins coarsely serrate (some of the lower leaves sometimes pinnately lacerate basally); [section Silphidium]

                            14 Leaves simple or compound, usually (but not always) some of the leaves on a plant with basal auricles or lobes, the leaf blades (or terminal leaflets) 0.5-3.5 cm wide, the margins entire; [section Coreopsis].

                              15 Stems with (5-) 6-12 nodes between the first node > 1 cm above the basal leaves and the first head.

                                16 Phyllaries primarily 9-12 mm long; laminae of rays ca. 20-30 mm long; peduncles 12-25 (-40) cm long

                                16 Phyllaries primarily 5-8 mm long; laminae of rays ca. 12-15 mm long; peduncles (7-) 12-15 cm long.

                                  17 Leaf blades (or terminal leaflets of compound leaves) narrowly oblanceolate, to 0.6 cm wide

                                  17 Leaf blades (or terminal leaflets of compound leaves) elliptical to oblanceolate, 0.6-4 cm wide.

                                    18 Leaf blades (or terminal leaflets of compound leaves) more or less broadly elliptical, ca. 1.5-4 cm wide, acute; stem (and often also the leaves) rather densely hairy (to glabrate)

                                    18 Leaf blades (or terminal leaflets of compound leaves) narrowly elliptical to oblanceolate, ca. 0.6-2 cm wide, acuminate; stem and leaves glabrous

                              15 Stems with 1-5 (-8) nodes between the first node > 1 cm above the basal leaves and the first head.

                                       19 Annual; rays yellow, with a red-brown or purple blaze or spotting near the base.

                                         20 Leaves extending >1/2 way up the stem; bracts subtending the phyllaries 6-9 (-12) mm long; disc corollas with apices red-brown to purplish; cypselae wingless

                                         20 Leaves extending <1/2 way up the stem; bracts subtending the phyllaries 4-6 (-8) mm long; disc corollas with apices yellow; cypselae winged.

                                           21 Inner phyllaries dorsally pubescent; stems typically glabrous (at least on mid-lower stems)

                                           21 Inner phyllaries dorsally glabrous; stems typically densely pubescent (sometimes sparsely so)

                                       19 Perennial (cormose or rhizomatous at base, and sometimes also stoloniferous); rays completely yellow, lacking a red-brown or purple blaze or spotting near the base.

                                             22 Plants lacking stolons; leaf blades (or terminal leaflets) > 3× as long as wide (basal leaves sometimes broader).

                                               23 Leaves oblanceolate, infolded, only very rarely with basal lobes, 15-30× as long as wide; leaf surfaces completely glabrous; [endemic to calcareous glades of Jackson County, FL]

                                               23 Leaves oblanceolate, not notably infolded, the larger often with basal lobes; leaf surfaces shortly pubescent at least along the veins; [widespread in our area]

                          13 Most or all of the leaves deeply lobed or dissected into distinct leaflets or divisions, the leaflets or divisions 3-20 or more, if only 3, then the lateral leaflets nearly or fully as large and well-developed as the terminal.

                                                 24 Leaves pinnately lobed into 3 (-5+) nearly parallel-sided lobes; [section Gyrophyllum].

                                                 24 Leaves compound with 3+ leaflets.

                                                    25 Leaves sessile or with a short subpetiolar base < 2 mm long, the initial division of the leaves palmate into 3 leaflets (these sometimes further divided), giving the 2 opposite leaves the superficial appearance of a whorl of 6 leaves; [section Gyrophyllum].

                                                      26 Leaves palmately 3-foliolate (rarely the leaves, especially the upper, simple, or with lower leaves 3-foliolate with the middle leaflet 2- or 3-lobed), the total number of leaflets or divisions thus (1-) 3 (-5), the middle leaflet of median leaves (2-) 5-30 mm wide

                                                      26 Leaves palmately compound, the leaflets simple to lobed or pinnatifid, the total number of leaflets or divisions (3-) 5-25, the middle leaflet of median leaves 0.5-7 mm wide.

                                                        27 Leaflets usually lobed (rarely simple), the total number of leaflets or divisions (3-) 5-11 (-15) per leaf, the segments of median leaves (1.5-) 2-7 (-9) mm wide

                                                        27 Leaflets pinnatifid, the total number of leaflets or divisions 11-25 or more per leaf, the segments of median leaves 0.2-2 (-2.5+) mm wide.

                                                          28 Midstem internodes 8-12 (-16) mm long; ultimate leaf lobes 1.0-1.5 (-2.5+) mm wide

                                                          28 Midstem internodes 15-40 (-60) mm long; ultimate leaf lobes 0.5-1.0 (-2.0) mm wide

                                                    25 Leaves, at least the lower, distinctly petioled on petioles 5-50 mm or more long.

                                                            29 Ray flowers not toothed terminally (or rarely with a few with inconspicuous and irregular teeth); mid-cauline leaves palmately 3-foliolate, the terminal leaflet sometimes again 3-5-foliolate (sometimes giving an appearance of a pinnately 5-7-foliolate leaf), the leaflets 6-35 mm wide, 3-15× as long as wide; [section Gyrophyllum]

                                                            29 Ray flowers apically with (2-) 4-5 teeth; mid-cauline leaves pinnately 5-11-foliolate, the leaflets either 3-15 mm wide and about 1-3× as long as wide, or 0.5-2 mm wide and > 20× as long as wide; [section Coreopsis].

                                                              30 Disk flowers reddish; ray flowers usually with a basal red mark; leaflets of mid-cauline leaves 1-15 mm wide and about 1-10× as long as wide

                                                                 31 Terminal leaflets of mid-cauline leaves 5-15 mm wide, < 3× as long as wide; [mainly sandy soils or in disturbed situations east of the Mississippi River]

                                                                 31 Leaflets of mid-cauline leaves 1-3 mm wide, 3-8× as long as wide; [mainly calcareous soils, in TX]

                                                              30 Disk flowers yellow; ray flowers yellow; leaflets of mid-cauline leaves 0.5-6 (-10) mm wide and > 10× as long as wide.

                                                                   32 Achene wings fimbriate; [of granitic outcrops of the Piedmont of GA and AL; disjunct in Ozark glades]

                                                                   32 Achene wings entire; [collectively more widespread].

                                                                     33 Midstem and upper stem leaves with 1-3 segments; plants reclining; flowering late Jun-Jul; [of dolomite glades in c. AL]

                                                                     33 Midstem and upper stem leaves with > 5 segments; plants erect; flowering May-late Jun; [of granite outcrops, sandy woods, and similar open disturbed areas; collectively more widespread].

                                                                       34 Larger segments of midstem and upper stem leaves 0.5-1.5 mm wide

                                                                       34 Larger segments of midstem and upper stem leaves 2-6 (-10) mm wide.

                                                                         35 Pappus teeth 0.5-1 mm long; [endemic to e. TX and s. OK]

                                                                         35 Pappus teeth ca. 0.2-0.3 mm long; [scattered from NC, SC, and GA westward to e. TX and e. OK]