1 Leaves evergreen.

  2 Plant a shrub, erect, not requiring support.

    3 Leaves with spiny margins; fruit a drupe; [uncommon horticultural escapes].

      4 Flowers 5-merous, the petals clawed; leaves usually small (ca. 2-3 mm long or less); [FL]

      4 Flowers 4-merous; petals not clawed; leaves larger (the longer leaves usually > 3 mm long); [NC northeastward]

    3 Leaves with crenate or serrate margins (the teeth not bearing small spines); fruits various; [widespread natives and non-natives]

        5 Leaves slightly to strongly fleshy; inflorescence a head; [maritime situations]

        5 Leaves not fleshy; inflorescence either a head or otherwise; [collectively widespread].

          6 Leaves > 8 cm long, typically spotted with yellow, coarsely toothed; fruit a red drupe; [commonly cultivated, rarely seeding down nearby]

          6 Leaves < 8 cm long, not yellow-spotted, serrulate; fruit a capsule or purplish drupe; [plants native or cultivated].

             7 Inflorescence otherwise; [more widespread].

               8 Corolla tubular, campanulate, bilaterally symmetrical; fruit a 1-seeded achene (rarely produced)

               8 Corolla radially symmetrical, with 4-5 distinct petals; fruit a 2-10-seeded capsule or drupe.

                 9 Fruit a 4-5-locular capsule, with 2 seeds per locule (though often fewer by abortion)

                 9 Fruit a (2-) 3-locular, purplish-black drupe, with (2-) 3 single-seeded stones

  2 Plant a subshrub, creeping shrub, or liana.

                   10 Leaves spinose-serrate; [exotics, rarely naturalized]

                   10 Leaves serrate (not spinose), serrulate, or crenate; [exotics and natives, collectively widespread].

                     11 Leaves slightly to strongly fleshy; inflorescence a head; [maritime situations]

                     11 Leaves not fleshy; inflorescence otherwise; [collectively widespread].

                       12 Leaves on vigorous shoots with a few coarse rounded teeth towards the base (most leaves entire)

                       12 Leaves serrulate to serrate, the teeth uniformly around the margin or concentrated towards the tip; fruit dry, either indehiscent and 1-seeded or capsular and with several seeds.

                          13 Flowers 5-merous; petals fused; fruit indehiscent, 1-seeded; [montane, from e. TN, WV, and w. MD northwards in our area]

                          13 Flowers 4- or 5-merous; petals separate; fruit capsular, dehiscent, several-seeded; [collectively widespread in our area]

1 Leaves deciduous.

                            14 Leaves slightly to strongly fleshy; inflorescence a head, subtended by an involucre of phyllaries; [maritime situations]

                            14 Leaves not fleshy; inflorescence, flower, and fruit structure various, but not with the combination of features as above (sometimes the flowers in a head subtended by bracts, but then with other features differing, such as stamens 4, or green calyx present, or petals separate, or fruit a schizocarp of mericarps, etc.); [collectively widespread].

                              15 Lianas climbing by twining or by adventitious roots.

                                16 Stems with retrorse prickles; foliage scabrous

                                16 Stems not prickly; foliage smooth to variously hairy, but not scabrous.

                                  17 Leaves on vigorous shoots with a few coarse rounded teeth towards the base (most leaves entire), the larger leaves < 3 cm wide; lianas climbing by twining; fruit a fleshy berry; flowers 5-merous, with a fused, tubular corolla

                                  17 Leaves serrate, the teeth towards the leaf apex, the larger leaves > 4 cm wide; lianas climbing by adventitious roots; fruit a capsule; flowers 7-10-merous, with separate petals

                              15 Upright shrubs or trees, lacking any adaptations for climbing.

                                    18 Trees; leaves often a mix of alternate and opposite.

                                       19 Leaves harshly scabrous on the upper surface; fruit a multiple of achenes; leaf venation pinnate but irregular

                                       19 Leaves not scabrous; fruit a 2-4-seeded drupe; leaf venation neatly pinnate, the lateral veins nearly straight and parallel to one another

                                    18 Shrubs or trees; leaves strictly opposite (or often subopposite in RHAMNACEAE).

                                         20 Trees; leaves palmately-veined, with 5 or more veins from the base; [rarely naturalizing]

                                         20 Shrubs; leaves either triple-veined from near the base or pinnate-veined; [collectively widespread and common]

                                           21 Leaves strongly triple-veined from at or near the base of the blade, the 2 lateral veins arching towards the tip and rejoining the midvein or nearly so (becoming diffuse before rejoining); petals 4, white; stamens 15-90

                                           21 Leaves pinnate-veined; petals various, not both 4 and white (except sometimes in Hydrangea); stamens 1-15 (except 15-30 in Exochorda in ROSACEAE).

                                             22 Inflorescence head-like; flowers sympetalous and 4-lobed; fruit 2 seeded

                                             22 Inflorescence more diffuse, with internal axes and pedicels; flowers not BOTH sympetalous and 4-lobed (except in Forsythia and Buddleja, which have conspicuous axillary or paniculate inflorescences); fruit 1-seeded, 2-4-seeded, or 4-many-seeded.

                                               23 Plants in flower.

                                                 24 Corolla absent; flowers inconspicuous and small, in axillary fascicles or catkins.

                                                    25 Flowers in catkins; leaves usually a mix of opposite and alternate

                                                    25 Flowers in axillary fascicles; leaves strictly opposite (subopposite)

                                                 24 Corolla present; flowers larger, in terminal cymes, corymbs, racemes, panicles, or in axillary cymes or fascicles.

                                                      26 Petals separate; stamens 8-10 (-60) (or 4-6 in RHAMNACEAE and Euonymus in CELASTRACEAE).

                                                        27 Flowers 1-few, in axillary cymes; stamens 4-6; stems brown, tan, gray, or green.

                                                          28 Leaf venation pinnate, but irregular and reticulated; stems green

                                                          28 Leaf venation neatly pinnate, the lateral veins nearly straight and parallel to one another; stems brown, tan, or gray

                                                        27 Flowers 1 and terminal, or many, in terminal panicles or corymbs; stamens 8-10 (-60); stems brown, tan or gray.

                                                            29 Inflorescence a solitary, terminal flower; stamens 30-60

                                                            29 Inflorescence a terminal panicle or corymb; stamens 8-15

                                                      26 Petals fused, at least basally, and often strongly tubular; stamens 2, 4, or 5.

                                                              30 Stamens 5.

                                                                 31 Petals white, fused basally only, the lobes spreading

                                                                 31 Petals pink, yellow, or reddish, fused for most of their length

                                                              30 Stamens 2 or 4.

                                                                   32 Stamens 2; petals yellow; flowers radially symmetrical; inflorescence an axillary fascicle

                                                                   32 Stamens 4; petals white, pink, or lavender; flowers bilabiate; inflorescence a terminal thyrse or panicle or an axillary cyme.

                                                                     33 Petals 4; inflorescence a terminal thyrse

                                                                     33 Petals 5; inflorescence a terminal panicle or an axillary cyme.

                                                                       34 Inflorescence an axillary cyme

                                                                       34 Inflorescence a terminal panicle

                                                                         35 Flowers lavender; fruit a shiny orange drupe (appearing berry-like)

                                                                         35 Flowers pinkish-white; fruit a bristly achene

                                               23 Plants in fruit.

                                                                           36 Fruit a berry, drupe, or achene, indehiscent, fleshy at maturity (or dry in Kolkwitzia).

                                                                              37 Fruit a berry, with 20+ seeds

                                                                              37 Fruit a drupe or achene, with 1-4 seeds.

                                                                                38 Fruit an achene (1-seeded), dry at maturity

                                                                                38 Fruit a drupe (1-4-seeded), fleshy at maturity.

                                                                                  39 Inflorescence a terminal corymb

                                                                                  39 Inflorescence axillary, fascicled or a cyme.

                                                                                    40 Foliage with stellate hairs; fruit a pink-purple 4-seeded drupe

                                                                                    40 Foliage glabrous or with simple hairs; fruit a dark red, black, or blue 1-4-seeded drupe.

                                                                                      41 Fruit a 1-seeded drupe; [NC southwards and westwards]

                                                                                      41 Fruit a 2-4-seeded drupe; [widespread in our region]

                                                                           36 Fruit a capsule, dehiscent, dry at maturity.

                                                                                        42 Inflorescence a catkin, the flowers small (< 5 mm in diameter) and tightly arranged on the inflorescence axis (> 5 per cm of the axis)

                                                                                        42 Inflorescence various, but more diffuse, the flowers larger (> 5 mm in diameter, except for some flowers in Hydrangea in HYDRANGEACEAE) and loosely arranged (< 5 per cm of axis).

                                                                                           43 Capsule prominently 5-angled (star-shaped in ×-section)

                                                                                           43 Capsule not angled.

                                                                                             44 Inflorescence axillary, fascicled.

                                                                                               45 Capsule pink to red; fruits solitary or in axillary cymes

                                                                                               45 Capsule brown; fruits in axillary fascicles

                                                                                             44 Inflorescence terminal, a raceme, panicle, corymb, or compound cyme or thyrse.

                                                                                                 46 Inflorescence a flat-topped corymb or rounded compound cyme, as wide as or wider than long

                                                                                                 46 Inflorescence elongated, a raceme, panicle, or thyrse, much longer than wide.

                                                                                                   47 Capsule elongate (> 3× as long as wide), 8-25 mm long

                                                                                                   47 Capsule about as long as wide, 3-6 mm long.

                                                                                                     48 Sepal lobes 5

                                                                                                     48 Sepal lobes 4

1 Leaves opposite, at least on the lower stem nodes (the leaves higher on the stem sometimes alternate); [tribe Heliantheae or tribe Eupatorieae].

  2 Heads radiate, the rays yellow to orange; disc flowers yellow to orange.

    3 Leaves linear; receptacle epaleate, but densely setose; [extreme s. TX]

      4 Leaves mostly entire, rarely distally 3-lobed, often somewhat glaucous; disc florets 30-100+; receptacle densely setose; pappus of scales

      4 Leaves usually shallowly to deeply 3-9-lobed, green; Disc florets 100+; receptacle with oblong-rectangular paleae; leaves linear or linear-lobed; pappus absent

    3 Leaves lanceolate or broader, 1-5× as long as wide; receptacle paleate; heads borne singly or many; [collectively widespread].

        5 Leaves ovate, rhombic, or pentagonal, unlobed or 3-5-(-7) lobed; leaf blade margins toothed; leaves in part alternate upwards; [of disturbed, suburban areas of FL peninsula]; [tribe Heliantheae; subtribe Helianthinae]

          6 Ray laminae 5-16 mm long; leaf blades 7-33 cm long, the larger deeply 3-7-lobed; petiole bases dilated at base, fused to form a disc of leaf tissue at the stem

          6 Ray laminae 45-70 mm long; leaf blades 2-8 cm long, unlobed or 3-lobed; petiole bases not dilated at base

        5 Leaves lanceolate to oblanceolate, unlobed or obscurely 3-lobed; leaf blade margins toothed or entire; leaves strictly opposite; [tribe Heliantheae; subtribe Ecliptinae].

             7 Leaves obovate to oblanceolate, unlobed, entire; heads (5-) 8-13 (-18+) mm in diameter; cypselas 3-4-smgled, not winged; [of tidally inundated salt and brackish marshes of the outer Coastal Plain, MD to s. FL, west to s. TX]

             7 Leaves lanceolate, sometimes 3-lobed, usually serrate but sometimes nearly entire; heads 4-8 mm in diameter; cypselas flattened and winged; [TX only]

  2 Heads discoid or disciform (ray flowers lacking); disc flowers pink, purple, whitish, yellow, or orange.

               8 Disc flowers yellow to orange

               8 Disc flowers pink, purple, or white.

                 9 Heads small (involucres 2-8 mm high), solitary, axillary in the axils of leaves or leafy bracts (similar to the leaves but smaller) or interpretable as arrayed in bracteate racemes; heads nodding, the involucre 2-7 mm high; [collectively widespread in coastal portions of our area, of maritime situations]; [tribe Heliantheae; subtribe Ambrosiinae]

                 9 Heads small to larger (involucres 3-15+ mm high), many, terminal on the branches of corymbiform or paniculiform arrays; heads erect, the involucre 4-12 mm high; [of Coastal Plain of FL, s. GA, and TX].

                   10 Pappus of 4-10 scales, 0.3-7 mm long; [tribe Heliantheae; subtribe Chaenactidinae]

                   10 Pappus of 5-70 barbellate bristles, 3-12 mm long; [tribe Eupatoriae]

                     11 Leaf blades spatulate to obovate, cuneate to attenuate at the base, rounded or shallowly notched at the apex; leaf margins entire; leaves opposite below, alternate higher on the stems; [native of FL]

                     11 Leaf blades triangular or lanceolate, truncate, cordate, or cuneate at the base, acute to acuminate at the apex; leaf margins serrate; leaves opposite throughout.

                       12 Phyllaries broad, 2-3× as long as wide, the inner phyllaries translucent-scarious white to pinkish at their broadly rounded apices, falling as the head goes to fruit

                       12 Phyllaries narrow, 4-7× as long as wide, the inner phyllaries green at their acute to acuminate apices, persistent on the head in age.

                          13 Involucres 3-7 mm in diameter; phyllaries 25-35 in 2-3 series; disc flowers 10-60 per head; [TX only (in our region)].

                            14 Disc flowers white (to light pink); [c. TX]

                            14 Disc flowers blue to lavender (rarely white); [extreme s. TX]

1 Leaves strictly alternate.

                              15 Heads radiate (with ray and disc flowers) or pseudoradiate (with pseudoradiate flowers only.

                                16 Rays white, pink, or rose.

                                  17 Rays pink or rose, 30-50 (-70); sprawling viny shrub to 40 dm tall; leaves ovate, averaging ca. 3× as long as wide, with clasping base, with a midvein and lateral veins and tertiary reticulation

                                  17 Rays white, 5-34+; shrubs 2-30 dm tall; leaves either obovate to oblanceolate, averaging ca. 4× as long as wide, dentate, or linear, ca. 10× as long as wide, entire, cuneate.

                                    18 Rays white, 5-11 (-15); leaves linear, ca. 10× as long as wide, entire; [native, s. and se. TX]

                                    18 Rays white, 21-34+; leaves obovate to oblanceolate, averaging ca. 4× as long as wide, dentate; [non-native, known in our region only from NY]

                                16 Rays or pseudorays yellow, orange-yellow, or light creamy yellow.

                                       19 Heads pseudoradiate, with 11-25 pseudoray flowers and 0 disc flowers; leaves 8-70 mm wide

                                       19 Heads radiate, with (0-) 1-11 (-15) ray flowers and 1-15 (-20) disc flowers; leaves (or their segments) 0.5-10 mm wide.

                                         20 Phyllaries in 1-2 series and equal or subequal in length to one another, the phyllaries often coherent/fused (the involucre thus appearing as a cylinder with ribs extending from base to top; calyculus (of bracts subtending the phyllaries and differing from them in texture, color, or orientation) present; [tribe Senecioneae]

                                         20 Phyllaries in 3-17 series and unequal in length (imbricated); calyculus absent.

                                           21 Rays light creamy yellow, 5-11 (-15); involucre 3-5 (-7) mm in diameter

                                           21 Rays bright yellow, (0-) 1-9; involucre 1-2.5 (-3) mm in diameter.

                                             22 Pappus of 40-60 barbellate bristles; ray blades 4-6 mm long; leaf surfaces minutely pebbled; intricately branched shrubs to 1 m tall, with persistent sterile shoots with evergreen leaves and annual flowering shoots (the entire shoot and leaves deciduous); [Coastal Plain, se. NC south to Panhandle FL and s. MS]

                                             22 Pappus absent, a low coroniform structure, or of scales; ray blades 2-3.5 mm long; leaf surfaces planar/revolute; shrubs 1-15 dm tall, not differentiated into evergreen, sterile shoots bearing deciduous, fertile shoots; [OK and TX westwards, very rarely as a waif eastwards].

                                               23 Pappus of 5-10 elongate scales

                                               23 Pappus absent or a low (< 0.1 mm high) crown

                              15 Heads discoid (with disc flowers only).

                                                 24 Pappus absent; leaves 1-2× pinnately or 1× palmately lobed.

                                                    25 Leaves either palmately 3-lobed, or pinnately lobed and the few (<11) lobes > 2 mm long

                                                    25 Leaves 1-pinnately lobed, the many (>21) lobes mostly < 1.5 mm long and wide

                                                 24 Pappus of bristles; leaves unlobed (the margins entire or serrate).

                                                      26 Plants dioecious, either male or female; heads either staminate, with 10-50 flowers, or pistillate, with 20-150 flowers

                                                      26 Plants hermaphroditic; heads bisexual, with 5-25 flowers, either all perfect (bisexual), or a mixture of perfect (bisexual) and functionally staminate flowers.

                                                        27 Leaves strongly basally disposed, crowded in the lowermost, woody or semiwoody portion of the stem

                                                        27 Leaves on the stem.

                                                          28 Leaves lanceolate to ovate (broadest below the midpoint); leaf margins entire to coarsely toothed.

                                                            29 Heads in leafy, paniculate arrays; leaf blades coarsely dentate, 0.5-4 cm long; shrubs to 12 dm tall; [c. and e. TX]

                                                            29 Heads borne in leafless, corymbiform arrays; leaf blades entire to denticulate, 5-16 (-20) cm long; shrubs to 40 dm tall; [FL and s. TX]

                                                          28 Leaves obovate, spatulate, or orbiculate (with rounded apex) or elliptic (with acute to acuminate apex), broadest at or beyond the midpoint; leaf margins entire.

                                                              30 Leaf blades obovate, spatulate, or orbiculate, rounded or slightly notched at the apex; leaf blade surfaces gray-green on both surfaces, granular when young; disc flowers 5 per head; [FL]

                                                              30 Leaf blades elliptic, acute to acuminate at the apex; leaf blade strongly bicolored above and below, the upper surface dark green and glabrate, the lower surface densely and finely tomentose and strongly whitened, the upper surface dark green and glabrate or glabrous; disc flowers 4-25 per head; [s. TX]