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 2-3 mm in diameter; phyllaries 7-16 in 1-2 series; disc flowers 3-13 per head; [s. FL only (in our region)]

                          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 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]

1 Pappus absent, or of crowns (coroniform) or scales (the scales entire, erose, aristate, or occasionally lacerate, but ultimately with broadened bases compared to bristles).

  2 Stems usually winged from decurrent leaf bases (except H. amarum, which bares stems with copious, mostly entire, linear leaves)

  2 Stems not winged.

    3 Pappus absent.

      4 Phyllaries in (3-) 4-9+ series, usually with apices hooked or looped; pappus of setiform awns or scales but falling (thus sometimes appearing absent post maturation)

      4 Phyllaries in 2-4 series, usually with apices not notably hooked or looped; pappus absent entirely (not just falling).

        5 Receptacles pitted and hairy (the hairs swollen and apically hooked); [primarily native in western portion of our area]

        5 Receptacles not pitted, nor hairy; [waifs].

          6 Leaves usually 1-3 pinnately lobed; receptacles epaleate

          6 Leaves entire or sometimes toothed, but not pinnately lobed; receptacle epaleate or sometimes with short bristles or setae

    3 Pappus coroniform or of scales.

             7 Heads smaller, the involucres (excluding phyllary apices) 0.8-7.5 mm in diameter.

               8 Ray floret laminae fan-shaped and apically 3 or 5 lobed (the laminae sometimes very short and not surpassing phyllary length in Hymenoxys).

                 9 Cauline leaves pronounced, simple or with 3-19+ lobes (the lobes linear-filiform); cypselae villous or pubescent (rarely glabrous); heads radiant, sometimes appearing nearly discoid due to diminutive or inconspicuous ray florets

                 9 Leaves strongly basally-disposed (except T. linearifolia, with basal and cauline leaves, the cauline leaves not with linear lobes), entire or with 2-6 teeth (or sometimes lobes); cypselae moderately to densely pubescent; heads clearly radiate

               8 Ray floret laminae not apically 3-5 lobed.

                   10 Leaves pinnately compound with linear leaf segments 1-3 mm wide (if not pinnate as in T. tephroleuca, then plants ashy white subshrubs); calyculus present (occasionally absent), of linear bracts subtending the involucre; plants with translucent oil glands evident throughout most parts; [subtribe Pectidinae]

                   10 Leaves simple (if also sometimes subshrubs, these not ashy white as in Gutierrezia); calyculus absent; plants sometimes gland-dotted on leaves (or sometimes also with resinous phyllaries, but not with oil glands throughout).

                     11 Plants annual, with a strong terpenoid smell when crushed, the leaves and phyllaries glutinous; phyllaries 12-15 in 1-2(-3) series

                     11 Plants annuals, biennials, or perennials, if annuals then not bearing a strong terpenoid smell when crushed, the leaves sometimes glutinous but not also the phyllaries; phyllaries 4-40 in 2-4 series (Gutierrezia) or 5-12 in 1-2 series (Psilostrophe).

                       12 Stems arachno-villous, appearing gray-green; involucre 4-7 mm in diameter; plants biennials or perennials; phyllaries 5-12 in 1-2 series

             7 Heads larger, the involucres (8-) 10-20+ mm in diameter.

                          13 Phyllaries in (3-) 4-9+ series; cypselae glabrous; leaves often toothed (and also often ovate to oblanceolate).

                            14 Pappus in 2 series, the outer of 25-40 barbellate bristles, the inner of 8-15+ setiform awns or subulate scales 7-10 mm long

                            14 Pappus in 1 series, of mostly 2-3 smooth to setiform awns OR subulate scales 2.5-8 mm long (sometimes with up to 6-8 total barbellulate/setiform awns in G. squarrosa, G. lanceolata, and G. texana)

                          13 Phyllaries in 2-3 series (2-3+ in Gaillardia); cypselae villous or otherwise sparsely to densely pubescent; leaves entire, toothed, or sometimes pinnately lobed (the lobes linear, as in Hymenoxys).

                              15 Receptacles entirely epaleate, not bearing any minute setae; ray florets (apical portion of the laminae) 3-5 lobed.

                                16 Cauline leaves pronounced, simple or with 3-19+ lobes (the lobes linear-filiform); cypselae villous or pubescent (rarely glabrous); heads radiant, sometimes appearing nearly discoid due to diminutive or inconspicuous ray florets

                                16 Leaves strongly basally-disposed (except T. linearifolia, with basal and cauline leaves, the cauline leaves not with linear lobes), entire or with 2-6 teeth (or sometimes lobes); cypselae moderately to densely pubescent; heads clearly radiate

                              15 Receptacles typically with spine-like setae or enations (except Gaillardia aestivalis) or very short bristles (i.e. not appearing "chaffy" overall, but these setae apparent upon dissection of the heads); ray florets (apical portion of the laminae) either unlobed (Amblyolepis) or 3-5 lobed (Gaillardia).

                                  17 Plants sweet-scented; cypselae prominently 10-ribbed; pappus scale apices rounded to acuminate but never aristate; heads borne singly or in paniculiform arrays; ray florets (the laminae) yellow; phyllaries usually not strongly reflexed in fruit

                                  17 Plants not sweet-scented; cypselae ca. 4-angled but lacking numerous prominent ribs; pappus scale apices often aristate; heads borne singly; ray florets (the laminae) often bicolored; phyllaries usually strongly reflexed in fruit

1 Pappus of barbellate to barbellulate bristles (sometimes also with shorter outer scales).

                                    18 Phyllaries in one series.

                                       19 Plants herbaceous vines; flowers conspicuously orange; calyculus of lanceolate-filiform bractlets; [non-native, FL and TX]

                                       19 Plants not herbaceous vines; flowers primarily yellow (sometimes yellow-orange); calyculus absent (or 1-2 indistinct bractlets); [natives or non-natives, collectively widespread]

                                         20 Pappus bristles red, brown, or purple colored; flowers yellow to yellow-orange; [waif, MD]

                                         20 Pappus bristles white; flowers primarily yellow; [native and non-native, widespread]

                                           21 Disc florets sterile; stems bracteate but lacking leaves, the leaves simple; [non-native of disturbed habitats, ne US]

                                           21 Disc florets fertile; stems with leaves, the leaves simple to pinnately lobed (or otherwise compound); [natives and non-natives, widespread and of both intact and disturbed habitats].

                                             22 Stem leaves deeply toothed, pinnately lobed, or otherwise compound, not clasping or weakly so; plants perennial or rarely annuals (P. glabella)

                                             22 Stem leaves shallowly toothed to subentire, conspicuously clasping the stem; plants annuals

                                    18 Phyllaries in 2-8+ series.

                                               23 Plants herbaceous vines; flowers conspicuously orange

                                               23 Plants not herbaceous vines; flowers primarily yellow (sometimes yellow-orange)

                                                 24 Pappus double, of both an inner (more apparent) series of longer bristles and an outer series consisting of short triangular scales or significantly shorter (and often coarser) bristles, these sitting more or less at the base of the inner pappus bristles (in Prionopsisthe outer bristles subtend the inner awns or scales).

                                                    25 Plants usually gland-dotted; phyllaries often looped/hooked; outer bristles subtending inner scales; involucres globose/hemispheric

                                                    25 Plants glabrous, sericeous, or glandular; phyllaries often ascending, sometimes squarrose; pappus scales subtending inner bristles; involucres variously shaped.

                                                      26 Outer pappus of scales connate, usually forming cups; ray laminae often reduced, 1.5-2+ mm long; [waifs; tribe Inuleae]

                                                      26 Outer pappus not connate; ray laminae prominent, usually > 3 mm longer; [native, sometimes weedy; tribe Astereae].

                                                        27 Ray florets without pappus

                                                        27 Ray florets with pappus (similar to that of disc florets).

                                                          28 Leaves parallel-veined, linear and grasslike

                                                          28 Leaves pinnately veined, usually broader and not grass-like.

                                                            29 Plants biennials or perennials, with taproots or fibrous-rooted; phyllaries linear-lanceolate to oblanceolate; inner pappus whitish to stramineous, outer pappus linear to narrowly-triangular

                                                            29 Plants annuals with taproots; phyllaries linear to linear-lanceolate; inner pappus yellow to rust-colored proximally, outer pappus scale-like; disc florets bisexual and fertile (B. pilosa) or functionally staminate (B. hirtella)

                                                 24 Pappus simple, of only bristles and not with an additional series of reduced bristles or scales (sometimes pappus in 2-4 unequal series, or outer bristles progressively shortened in Xanthisma).

                                                              30 Leaves toothed and tipped with spines (spinulose).

                                                                 31 Phyllaries spine-tipped with accompanying white margins (if lacking spine tips as in X. texanum, then inner phyllaries abruptly enlarged into ovate or sometimes elliptic blades 2-5 mm wide)

                                                                 31 Phyllaries not spine-tipped and lacking conspicuous white margins, 0.9-1.7 mm wide.

                                                              30 Leaves entire or if toothed, not tipped with conspicuous spines (as in Grindelia).

                                                                   32 Ray florets longer, 1.5-3+ cm long; anthers tailed; leaf bases conspicuously cordate-clasping

                                                                   32 Ray florets shorter, < 1.5 cm long (to 1.6 cm in Grindelia lanceolata); anthers not tailed (instead obtuse to sagittate), or if sagittate-tailed, then plants foul-smelling (as in Dittrichia, a waif in ne. US).

                                                                     33 Plants viscid, foul-smelling; anthers sagittate-tailed at the base [waif, ne. US]

                                                                     33 Plants scentless, or if bearing an odor, not foul-smelling; anthers cuneate to sagittate at the base, but not tailed; [widespread natives, rarely e. US waifs otherwise native to w. US].

                                                                       34 Pappus bristles > 60 (30-80+ in Senecio), white-colored.

                                                                         35 Stem leaves deeply toothed, pinnately lobed, or otherwise compound, not clasping or weakly so; plants perennial or rarely annuals (P. glabella)

                                                                         35 Stem leaves shallowly toothed to subentire, conspicuously clasping the stem; plants annuals

                                                                       34 Pappus bristles 10-45 (30-80+ in Senecio), white, tawny, or reddish-brown colored.

                                                                           36 Phyllaries in 1-2 equal/subequal series (outer minute bracts sometimes present); stem leaves shallowly toothed to subentire, conspicuously clasping the stem; plants annuals; [tribe Senecioneae)

                                                                           36 Phyllaries in 3+ series, unequal (or rarely subequal); [tribe Astereae].

                                                                              37 Heads small and cylindrical, taller than wide; rays inconspicuous or the laminae often shorter.

                                                                                38 Inflorescences flat-topped corymbs; leaves resinous-punctate, narrow, entire, sessile or subsessile

                                                                                38 Inflorescences rarely flat-topped; leaves not resinous-punctate, usually not linear, often toothed and petiolate

                                                                              37 Heads larger, globose, hemispheric, or broadly conic (2 cm+ broad in Grindelia), usually wider than long; rays conspicuous.

                                                                                  39 Leaves entire, sessile throughout; faces of cypselae strigose to sericeous; pappus persistent, of 30-35 tawny to reddish-brown barbellate bristles

                                                                                  39 Leaves toothed, proximal leaves petiolate; faces of cypselae variously textured (smooth, striate, furrowed, or rugose); pappus readily falling, of 2-3 smooth to setiform awns OR subulate scales 2.5-8 mm long (sometimes with up to 6-8 total barbellulate/setiform awns in G. squarrosa, G. lanceolata, and G. texana)