1 Leaves all basal, from creeping rhizomes; corolla white; [subfamily Solanoideae].

  2 Leaves broadly elliptical, rounded at the base; corolla lobes > 2× as long as wide, attenuate at the tip; [tribe Jaboroseae]

1 Leaves all or mainly cauline.

    3 Plant distinctly woody, an upright shrub or scrambling vine.

      4 Corolla ≥ 16 cm long.

        5 Plants vines

        5 Plants large shrubs to small trees

      4 Corolla < 16 cm long.

          6 Flowers white or yellow, the tube > 6× as long as its diameter; fruit either a white berry, or a capsule.

             7 Fruit a white, purple, or black berry; [subfamily Cestroideae; tribe Cestreae]

             7 Fruit a capsule; [subfamily Nicotianoideae]

          6 Flowers lavender or blue, the tube < 3× as long as its diameter; fruit a red, orange, or yellow berry; [subfamily Solanoideae].

               8 Leaves 0.5-7 cm long, 0.2-3.5 cm wide; [tribe Lycieae]

               8 Leaves 10-30 cm long, 4-14 cm wide; [tribe Solaneae]

    3 Plant herbaceous (some taxa keyed here can be robust and tough-stemmed, but are herbaceous, lacking overwintering buds on aerial stems).

                 9 Corolla salverform or narrowly funnel-shaped, with a well-developed tubular portion, this > 1 cm long (except in Calibrachoa) and either flared or essentially isodiametric and > 4× as long as its midpoint diameter, the limb expanding more or less abruptly from the tubular portion; fruit a capsule opening by longitudinal valves or by apical pores.

                   10 Corolla 7-25 cm long, white, pale blue or pale pink; capsule spiny, 3-5 cm long, subtended by a collar formed by the reflexed corolla base; [subfamily Solanoideae; tribe Datureae]

                   10 Corolla 0.6-7 cm long, white, blue, pink, or other colors; capsule smooth, not collared.

                     11 Flowers solitary, axillary; [subfamily Petunioideae].

                       12 Leaves linear to narrowly spatulate

                       12 Leaves oblong, ovate or elliptic

                     11 Flowers in (2-) 3-many flowered racemes or panicles.

                          13 Calyx accrescent in fruit, wholly or partly surrounding the capsule; corolla lavender to blue, with a whitish center; flower bilaterally symmetrical; stamens 4; [subfamily Cestroideae; tribe Browallieae]

                          13 Calyx not accrescent, subtending the mature fruit; corolla white, pink, green, pink, or blue; flower radially symmetrical; stamens 5.

                            14 Leaves broad, > 4 cm wide; corolla tube 1.5-12.0 cm long; [subfamily Nicotianoideae]

                            14 Leaves narrow, linear to narrowly oblancolate, to 0.5 mm wide; corolla tube 1.0-1.4 cm long; [subfamily Petunioideae]

                 9 Corolla either urceolate, campanulate, or rotate, lacking a narrow tubular portion that is both > 1 cm long and > 4× as long as its midpoint diameter; fruit a berry (or circumscissile capsule in Hyoscyamus); [subfamily Solanoideae].

                              15 Fruit a circumscissile capsule; calyx accrescent, nearly enclosing the fruit; corolla cream to yellow, with a maroon center; inflorescence a strongly secund raceme; [tribe Hyoscyameae]

                              15 Fruit a berry (hollow in Capsicum); calyx either accrescent around the fruit or not (and then subtending the fruit); corolla various (but not as above, though in some Physalis yellow and with each petal marked with a purple or maroon spot); inflorescence various.

                                16 Calyx not accrescent, subtending the mature berry.

                                  17 Berries 1.0-2.5 cm long; corolla urceolate (at least slightly constricted at the ‘neck’, just below the lobes of the corolla).

                                    18 Berries nearly spherical, blue-black, 1.0-2.0 cm long, 1.0-2.0 cm in diameter; corolla 2-3 cm long, maroon or purple, and greenish towards the base; plant an upright herb; [tribe Hyoscyameae]

                                    18 Berries elliptical, yellow, 1.5-2.5 cm long, 0.8-1.5 cm in diameter; corolla white 0.7-1.0 cm long, white; plant a trailing or scrambling vine; [tribe Physaleae]

                                  17 Berries 0.3-25 cm long.

                                       19 Locules air-filled; berries usually elongate and irregularly shaped (sometimes ovoidal or spherical; [peppers, chilies]; [tribe Capsiceae]

                                       19 Locules fleshy; berries spherical or ellipsoidal; [nightshades, tomato, potato, eggplant]; [tribe Solaneae]

                                16 Calyx accrescent, wholly or partly surrounding the mature berry.

                                         20 Mature calyx spiny; [tribe Solaneae]

                                         20 Mature calyx glabrous or with hairs.

                                           21 Calyx divided nearly to the auricled base; corolla blue; [tribe Nicandreae]

                                           21 Calyx fused nearly to its summit; corolla white or yellow; [tribe Physalinae].

                                             22 Fruiting calyx bright red (fresh or dry); corolla white; [cultivated and weakly naturalized near gardens]

                                             22 Fruiting calyx green, yellow, or orange, drying brown or tan; corolla yellow, often marked with 5 large maroon or purple spots in the throat; [collectively widespread].

                                               23 Flowers 2 or more per leaf axil; berries with spherical seed-like bodies intermixed with the flattened, reniform seeds; [of the Gulf Coastal Plain]

                                               23 Flowers 1 per leaf axil; berries with flattened, reniform seeds only; [collectively widespread]

1 Inflorescence an involucrate head subtended by phyllaries, the heads solitary or many and variously arrayed in secondary inflorescences, the ovary inferior, the corolla connate and tubular at least basally, the calyx absent, the stamens 5, the fruit a cypsela

1 Inflorescence, flower, and fruit structure various, but not with the combination of features as above (sometimes the flowers in a head subtended by bracts, e.g. Eryngium in APIACEAE, but then with other features differing, such as stamens 4, or green calyx present, or petals separate, or fruit a schizocarp of mericarps, etc.).

  2 Basal leaves 2-lobed, pinnately lobed, or palmately lobed (not considering cordate, hastate, or auriculate leaf bases as “lobed”).

    3 Basal leaves 2-lobed, hinged between the lobes, each lobe with stiff, marginal, eyelash-like bristles; [Coastal Plain of NC and SC, rarely planted and weakly naturalized elsewhere]

    3 Basal leaves 3-many-lobed, palmately or pinnately; [collectively widespread].

      4 Leaf lobing pinnate.

        5 Gynoecium of separate pistils (each with a single carpel); fruit an aggregate

        5 Gynoecium of a single pistil (with 2, rarely more, carpels); fruit simple.

          6 Stamens many; sepals 2, petals 4; fresh plants with yellow, orange, or white milky juice

          6 Stamens 4, 5, or 6; sepals 4 or 5; petals 4 or 5.

             7 Petals 4, distinct; stamens 6

             7 Petals 5, fused; stamens 2, 4, or 5.

               8 Corolla radially symmetrical; stamens 5

               8 Corolla 2-lipped, bilaterally symmetrical or asymmetrical; stamens 2 or 4.

                 9 Corolla lobes not twisted, the flower bilaterally symmetrical; stamens 2

                 9 Corolla lobes twisted so as to make the flower asymmetrical; stamens 4

      4 Leaf lobing palmate.

                   10 Petiole attachment peltate.

                     11 Leaves < 10 cm in diameter

                     11 Leaves > 15 cm in diameter

                   10 Petiole attachment marginal.

                       12 Ovary inferior.

                          13 Petals 4; stamens 8; fruit a capsule

                          13 Petals 5; stamens 5; fruit a schizocarp of 2 mericarps.

                            14 Fruit tuberculate; leaves 3-lobed

                            14 Fruit smooth; leaves with 5 or more lobes

                       12 Ovary superior, or half-inferior by fusion of a hypanthium a part of the way up the ovary wall.

                              15 Gynoecium of separate pistils (each with a single carpel); fruit an aggregate.

                                16 Perianth of 5 green sepals and 5 colored petals.

                                  17 Carpels partly fused, arrayed in a ring of 10-20

                                  17 Carpels separate, spiral, many

                                16 Perianth of a single whorl of 3-12 petaloid sepals (the petals absent or small and rudimentary).

                                    18 Leaves 2, the single flower terminal and associated with the upper leaf; fruit an aggregate of berries

                                    18 Leaves normally > 2, flowers not as above; fruit an aggregate of achenes, utricles, or follicles

                              15 Gynoecium of a single pistil (with 1-5 carpels); fruit simple.

                                       19 Hypanthium present, partially fused or not fused to the pistil; ovary partially inferior to superior

                                       19 Hypanthium absent; ovary superior.

                                         20 Petals connate at base; leaves sharply toothed

                                         20 Petals distinct; leaves with rounded lobes or teeth.

                                           21 Corolla radially symmetrical; petals 8-12; capsule fusiform, narrowed to both ends, > 5× as long as wide

                                           21 Corolla bilaterally symmetrical; petals 5; capsule ovoid, < 2× as long as wide

  2 Basal leaves not lobed, at most serrate or crenate (and sometimes also cordate, hastate, auriculate, or peltate at the base).

                                             22 Basal leaves petiolate, the blade with a cordate, hastate, auriculate, or peltate base.

                                               23 Leaf margins entire.

                                                 24 Inflorescence a terminal and/or axillary raceme, panicle, or cyme of many small flowers; fruit an achene; perianth uniseriate, of 0, 4-5, or 6 tepals.

                                                    25 Flowers unisexual; staminate flowers 4-5 tepals, pistillate flowers lacking a perianth

                                                    25 Flowers bisexual; flowers with 6 tepals

                                                 24 Inflorescence either a terminal spike, or a 1-7-flowered terminal cyme, or of a solitary axillary or terminal flower; fruit various; perianth biseriate (of differentiated sepals and petals (except uniseriate, of 3 fused sepals in ARISTOLOCHIACEAE).

                                                      26 Flowers bilaterally symmetrical; inflorescence a terminal spike (with > 20 flowers); petals 4, usually scarious, transparent; sepals 4, green; stamens 4

                                                      26 Flowers radially symmetrical; inflorescence either of a solitary flower or of a 1-7-flowered terminal cyme; petals 5, 8-12, or 0; sepals 5 (green), 3 (brown), or 5-9 (yellow); stamens 5, 12, or many.

                                                        27 Gynoecium of separate pistils (each with a single carpel); fruit an aggregate of achenes or follicles; flowers bright yellow, either of 5-9 distinct petaloid sepals, or of 8-12 distinct petals subtended by 3-4 green distinct sepals

                                                        27 Gynoecium either of a single pistil with 6 carpels or of a single pistil with 4 carpels or of 2 nearly separate carpels; fruit a simple capsule (or deeply 2-lobed); flowers white, brown, or greenish, either of 5 fused or distinct white petals and 5 fused or distinct green sepals, or of 3 fused brown or greenish petaloid sepals.

                                                          28 Flowers brown or green, of 3 fused brown or greenish petaloid sepals (and 0 petals); carpels 6; stamens 12; leaves 4-10 cm wide

                                                          28 Flowers white, of 5 white or whitish petals and 5 green sepals; carpels 2; stamens 5; leaves 1-12 (-15) cm wide

                                                            29 Petals separate; sepals separate; plant glabrous

                                                            29 Petals fused (at least basally in Dichondra); sepals fused; carpels 2; plant pubescent.

                                                              30 Fruit a deeply 2-lobed capsule; sepals longer or ca. as long as petals; petals not undulate, fused at their bases or distal ½, the anthers maroon or brown-colored; [common, widespread in our area]

                                               23 Leaf margins crenate, serrate, or incised.

                                                                 31 Gynoecium of separate pistils (each with a single carpel); fruit an aggregate; perianth of 5 green sepals and 5 colored petals (or of 2 or 4 (-5) white-colored tepals in Begonia).

                                                                   32 Flowers typically with 2 or 4 (-5) white-colored tepals; leaf bases conspicuously oblique (sometimes variegated); fruit unequally or subequally 3-winged capsules; [ornamental waifs or uncommon non-natives]

                                                                   32 Flowers with 5 green sepals and 5 colored petals (not merged into tepals); leaf bases oblique or not; fruit various but not 3-winged capsules; [natives and non-natives].

                                                                     33 Carpels 10-20, partly fused, arrayed in a ring; petals white, pink, red, or purplish

                                                                     33 Carpels many, separate, spiral; petals yellow or white.

                                                                       34 Flowers lacking a hypanthium; fruit an aggregate of achenes or aggregate of follicles

                                                                       34 Flowers with a hypanthium; fruit an aggregate of drupelets or aggregate of achenes

                                                                 31 Gynoecium of a single pistil (with 1-5 carpels); fruit simple.

                                                                         35 Flowers bilaterally symmetrical; inflorescence of a solitary flower; fruit a 3-locular capsule

                                                                         35 Flowers radially symmetrical; inflorescence an umbel (or composite of umbelliform units, or a terminal panicle.

                                                                           36 Ovary superior; inflorescence a terminal panicle or terminal raceme.

                                                                              37 Inflorescence a terminal raceme; perianth of 4 green sepals and 4 white petals; fruit a silique/silicle; fresh foliage in spring and summer with a strong garlic odor; larger leaves < 10 cm in diameter

                                                                              37 Inflorescence a terminal panicle; perianth of 6 cream-colored petaloid sepals; fruit a winged achene; fresh foliage lacking a garlic odor; larger leaves typically > 30 cm in diameter

                                                                           36 Ovary inferior; inflorescence an umbel (or a composite of umbellate units); fruit a schizocarp of mericarps.

                                                                                38 Petiole attachment peltate

                                                                                38 Petiole attachment marginal (the blade cleft to the petiole.

                                                                                  39 Leaf blades longer than wide, sharply V-cleft at the base and otherwise shallowly denticulate

                                                                                  39 Leaf blades as broad or broader than long, cleft at the base and also irregularly serrate or crenate around the margin

                                             22 Basal leaves petiolate or not, with a truncate, rounded, or cuneate leaf base.

                                                                                    40 Leaves tubular, with a sutured ventral flange, erect or reclining, adapted as a pitfall for insects (flat, phyllodial leaves sometimes present as well, common in the winter in some species, such as S. oreophila)

                                                                                    40 Leaves flat, not sutured into a tubular shape.

                                                                                      41 Stem leaves opposite; perianth 5-merous, at least the corolla bilaterally symmetrical (barely so in VALERIANACEAE), or the parts curved so as to be asymmetrical (Pedicularis in OROBANCHACEAE); stamens 2, 3, or 4.

                                                                                        42 Ovary inferior; stamens 3

                                                                                        42 Ovary superior; stamens 2 or 4.

                                                                                           43 Corolla narrowly tubular, the five lobes flaring at nearly 90 degrees and nearly radially symmetrical

                                                                                           43 Corolla distinctly 2-lipped (with prominently large upper and lower corolla lobes) or hooded (the upper lip hood-like), distinctly bilaterally symmetrical, or the lobes twisted so as to make the corolla asymmetrical.

                                                                                             44 Corolla yellow, the upper lip often slightly to strongly maroon, hooded but the corolla lobes twisted so as to make the flower asymmetrical

                                                                                             44 Corolla white, lavender, or blue, 2-lipped and bilaterally symmetrical.

                                                                                               45 Sepals separate to the base or nearly so, not forming a tube

                                                                                               45 Sepals connate for at least 0.3× their length to form a tube

                                                                                      41 Stem leaves alternate; perianth radially symmetrical (less commonly bilaterally symmetrical); stamens 5, 6-8, 9, 10 (rarely 4).

                                                                                                 46 Ovary inferior (or half-inferior in Samolus).

                                                                                                   47 Perianth 4-merous; stamens 8

                                                                                                   47 Perianth 5-merous; stamens 5.

                                                                                                     48 Inflorescence an umbel; fruit a schizocarp of 2 mericarps

                                                                                                     48 Inflorescence an axillary or terminal raceme; fruit a capsule

                                                                                                 46 Ovary superior.

                                                                                                        49 Pistils many, each with a single carpel; fruit an aggregate of achenes

                                                                                                        49 Pistil 1, with 1-5 carpels; fruit simple (a legume, silique/silicle, capsule, utricle, or schizocarp of 4 nutlets).

                                                                                                          50 Corolla bilaterally symmetrical (barely so in Limosella in SCROPHULARIACEAE); stamens 2, 4, 6, 8, or 10.

                                                                                                            51 Stamens 6-8 or 10.

                                                                                                              52 Petals separate; stamens 10

                                                                                                              52 Petals fused; stamens 10 or 6-8.

                                                                                                                53 Stamens 10, monadelphous

                                                                                                                53 Stamens 6-8, epipetalous

                                                                                                            51 Stamens 2 or 4.

                                                                                                                  54 Stamens 2

                                                                                                                  54 Stamens 4.

                                                                                                                     55 [plants of coastal wetlands]

                                                                                                                     55 [plants of uplands or inland seeps or fens]

                                                                                                                       56 Flowers (and subtending bracts) red or yellow

                                                                                                                       56 Flowers purple, blue, or lavender

                                                                                                          50 Corolla radially symmetrical; stamens 5, 10, 4-6, or 9.

                                                                                                                         57 Perianth of 6 tepals; stamens 4-6 or 9; carpels 3

                                                                                                                         57 Perianth of green sepals and more brightly colored petals; stamens 5 or 10; carpels 2, 3, 4, or 5.

                                                                                                                           58 Leaves covered with sticky, gland-tipped hairs (often red), as flypaper traps for insects

                                                                                                                           58 Leaves lacking sticky gland-tipped hairs.

                                                                                                                             59 Fruit a schizocarp of 4 nutlets (ovary obviously 4-lobed in flower)

                                                                                                                             59 Fruit a capsule or silique/silicle (or utricle in Limonium in PLUMBAGINACEAE).

                                                                                                                               60 Inflorescence of a solitary, terminal flower; carpels 2-3 (-4).

                                                                                                                                  61 Corolla with a long tube and flaring corolla lobes (united > ½ its length)

                                                                                                                                  61 Corolla of separate petals or united only for a short length (< ¼ its length).

                                                                                                                                    62 Leaves serrate

                                                                                                                                    62 Leaves entire

                                                                                                                               60 Inflorescence of several to many flowers; carpels 5 (3 in Galax in DIAPENSIACEAE).

                                                                                                                                      63 Inflorescence an umbel; petals recurved, pink to almost white

                                                                                                                                      63 Inflorescence a raceme or panicle.

                                                                                                                                        64 Fruit a silique/silicle; petals 4; stamens 6

                                                                                                                                        64 Fruit either a capsule or a utricle; petals 5; stamens 5 or 10.

                                                                                                                                          65 Inflorescence a somewhat to very diffuse panicle, with 3 or more orders of branching, not giving at all the impression that the overall inflorescence is made of racemose units.

                                                                                                                                            66 Leaves entire; stamens 5; [plants of tidal marshes]

                                                                                                                                            66 Leaves serrate or crenate; stamens 10; [plants of various habitats, especially rock outcrops and bottomland forests and streambanks, never in tidal marshes]

                                                                                                                                          65 Inflorescence either a single terminal raceme (sometimes spike-like), or of 1 to several terminal and axillary racemes (these sometimes combined into a diffuse panicle, but one whose structure is clearly made up of many racemes).

                                                                                                                                               67 Inflorescence of 1-several terminal and axillary racemes, the plant typically well-branched, especially from the base; stamens 5

                                                                                                                                               67 Inflorescence of a single, terminal raceme, the plant unbranched; stamens 10 (or 5, with 5 staminodes)

                                                                                                                                                 68 Inflorescence spike-like, the flowers many (> 40), barely pedicelled; capsule 3-locular

                                                                                                                                                 68 Inflorescence a raceme, the flowers fewer (< 20) and distinctly pedicelled; capsule 5-locular