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Key to Asteraceae

Asteraceae

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(c) Horn, Jay
(c) Cressler, Alan M.
1 Plant a shrub or liana (woody vine), definitely with woody growth well above ground level
(c) Ward, Scott G
1 Plant an annual, biennial, or perennial herb, lacking woody growth above ground level (or suffrutescent at the base).
(c) Bradley, Keith
  2 Leaves opposite or whorled, at least on the lower stem nodes (the leaves higher on the stem sometimes alternate).
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
    3 Heads radiate, with both ray and disk florets present.
(c) Horn, Jay
  2 Leaves either alternate (not opposite even at lower nodes of the stem) or basal only (the heads on scapiform stems).
(c) Cressler, Alan M.
(c) Ward, Scott G - CC-BY
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
      4 Heads liguliflorous (composed of ligulate florets, the laminae flattened and strap-like); plant sap usually milky
(c) Sorrie, Bruce A. - CC-BY
(c) Fleming, Gary P.
(c) Bradley, Keith
(c) Cressler, Alan M.
(c) Ward, Scott G
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
(c) Bradley, Keith
      4 Heads not liguliflorous (the heads instead composed of disc florets (discoid, disciform) and/or ray florets (radiant, or radiate); plant sap usually clear.
(c) Murashkin, Stanislav - CC-BY
(c) Ward, Scott G
        5 Heads borne solitary on scapes, or many in a raceme on stems with only scale-like bracts.
(c) Bradley, Keith
        5 Heads borne on stems with leaves, the leaves alternate, opposite, or whorled on the stem, and sometimes also well developed basal leaves or rosettes.
(c) Weakley, Alan
(c) Fleming, Gary P.
(c) Ward, Scott G
(c) Ward, Scott G
          6 Heads discoid or disciform (composed primarily of disc florets and peripheral filiform florets), OR heads radiant, essentially composed of ordinary disc florets and dilated periphereal florets (these peripheral florets dilated, perfect, pistllate, or netural, but lacking broadly expanded laminae of ordinary ray florets).
(c) Sorrie, Bruce A. - CC-BY
             7 Leaves not spiny-margined; phyllaries spine-tipped or not; disk flowers variously colored (including pink)
(c) Ward, Scott G
(c) Sorrie, Bruce A. - CC-BY
               8 Pappus well-developed, of bristles, awns, scales, or a combination of these.
(c) Ward, Scott G
(c) Sorrie, Bruce A. - CC-BY
© Scott Ward
(c) Ward, Scott G
                 9 Pappus wholly or partially of scales (broad to narrow, sometimes almost bristle-like, but at least in part flattened) or awns (these often barbed)
(c) Ward, Scott G
(c) Cressler, Alan M.
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
          6 Heads radiate, with both central disc and peripheral ray florets, the ray florets with prominent laminae.
                   10 Rays yellow, cream, orange, or rarely red-tinged.
(c) Ward, Scott G
(c) Ward, Scott G
(c) Ward, Scott G
                     11 Receptacles naked (epaleate), rarely with imbedded bristles (or Gaillardia sometimes with short setae 1-6 mm long but these much shorter than the pappus scales of the cypselae)
                   10 Rays white, pink, purple, or bluish.
(c) Ward, Scott G - CC-BY
© Scott Ward
                       12 Pappus well-developed, of bristles, awns, scales, or a combination of these.
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Key to Asteraceae, Key A: woody composites (shrubs and lianas)

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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
        5 Leaves lanceolate to oblanceolate, unlobed or obscurely 3-lobed; leaf blade margins toothed or entire; leaves strictly opposite; [tribe Heliantheae; subtribe Ecliptinae].
(c) Weakley, Alan - CC0
             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]
(c) Shugart, Jody - CC-BY
             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 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]
 Iva
                 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].
© Scott Ward
                   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]
                       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 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.
                                  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.
(c) Horn, Jay
(c) Weakley, Alan
                                             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].
                                                        27 Leaves strongly basally disposed, crowded in the lowermost, woody or semiwoody portion of the stem
                                                              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]
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Key to Asteraceae, Key B: herbaceous composites with opposite or whorled leaves
and discoid or disciform heads (lacking ray florets)

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(c) Ward, Scott G - CC-BY
1 Pappus present, of 5-60 barbellate bristles; receptacle naked (without paleae or well-developed bristles); [tribe Heliantheae; subtribe Eupatoriae].
  2 Plant a twining herb, phyllaries and disk florets 4 per head
  2 Plant stiffly erect to sprawling but never twining, phyllaries and disk florets usually > 4 per head.
(c) Kinser, Abel - CC-BY-NC, permission granted to NCBG
    3 Leaves in whorls of 3-7, > 2 cm wide
    3 Leaves opposite, rarely alternate or whorled, if whorled, < 2 cm wide.
      4 Cypselae rostrate (with long beaks); the achene portion not bearing ribs
      4 Cypselae not beaked, the achene variously ribbed.
        5 Achenes (and ovaries) (3-) 4-5-ribbed; outer phyllaries not noticeably longitudinally striate.
          6 Heads pink to blue.
             7 Phyllaries in 2-4 series, persistent (or deciduous in Praxelis).
               8 Heads pink (rarely bluish); receptacles flat; florets 18-25 per head; leaves sometimes gland-dotted
               8 Heads blue; receptacles conic; florets 25-70 per head; leaves gland-dotted.
                 9 Bristles ca. 40; florets 25-30; phyllaries 15-25, unequal, deciduous (absence apparent in fruit)
          6 Heads white to cream or, rarely, pale lilac.
                     11 Phyllaries not strongly imbricate, with the principal ones subequal and sub-biseriate; petioles 0.5-10 cm
© Scott Ward
(c) Ward, Scott G - CC-BY
1 Pappus either absent, or of scales, setae, or awns; receptacle naked, paleate, or bearing bristles.
(c) lillybyrd - CC-BY-NC, permission granted to NCBG
(c) Wang, Zihao - CC-BY
                       12 Leaves whorled, linear, < 2 mm wide; head solitary; [aquatic herb growing in shallow stagnant water]
                       12 Leaves opposite (or alternate in part), broader in shape and > 5 mm wide; heads typically not solitary; [terrestrial or wetland plants].
© Scott Ward
                            14 Pappus of 2-12 scales; heads white, pink, or blue (yellow in Schkuhria).
                              15 Heads with 20-125 florets; leaves serrate or ± dentate (at least distally); [rarely naturalized exotics or s. TX/FL natives]; [tribe Eupatorieae].
                                16 Leaves petiolate; corolla tube glabrous, typically blue or lavender colored (sometimes white tinged); heads with 20-125 florets; [naturalized exotics or s. FL native]
                                16 Leaves sessile; corolla tube glandular-pubescent, typically white colored (sometimes pink-purple tinged); heads with 75-125 florets; [s. TX native]
                              15 Heads with 10-30 florets (or fewer in Schkuhria); leaves entire; [natives, of FL, s. GA, MS, and TX in our area]; [tribe Heliantheae; subtribe Chaenactidinae].
                                  17 Leaves 3-5 lobed (or foliolate); cypselae with curled hairs (Florestina tripteris) or villous on angles (Schkuhria pinnata); [s. TX in our area or ne. waif].
                                    18 Heads discoid, sometimes with 1 (-2) diminuitive rays, corolla (of discs) yellow; cypselae villous, at least at bases or on angles; [waif of ne US, native in sw. US]
© Scott Ward
(c) Ward, Scott G
                                  17 Leaves simple or unlobed; cypselae with straight hairs; [variously distributed in s. GA and FL w. to MO and s. TX]
                            14 Pappus none, or of a few bristles or irregular coroniform lobes; heads green to yellow.
                                       19 Heads bright yellow, closely aggregated into corymbiform arrays of flat-topped to dome-shaped glomerules
                          13 Receptacles with paleae or well-developed bristles (the pales sometimes modified into specialized perigynia or burs surrounding the achene).
                                           21 Involucre of four decussate, deltoid bracts (the outer two large and longer than and often enclosing the flowering heads); pappus absent; paleae tightly enclosing the cypselae; plants rooting at the nodes, sometimes free-floating in water; [uncommon non-native, c. FL]
                                           21 Involucre not of four decussate, deltoid bracts; plants not with the above combination of characters; [widespread natives and non-natives]
                                             22 Heads small, less than 1 cm in diameter at anthesis (the female heads enlarging in Xanthium); disc florets dull white or suffused with green or purple; florets mainly unisexual (either in the same heads and then males central and females peripheral, or in separate female and male heads); female florets 0-8 per head; [tribe Heliantheae; subtribe Ambrosiinae].
                                               23 Heads unisexual; cypselas shed within an indurated bur or “nut” with hooked or straight spines developed from the phyllaries and/or paleae.
                                               23 Heads bisexual, with functionally male and female flowers in the same head; cypselas shed individually, not enclosed.
                                             22 Heads larger, mostly > 1 cm in diameter at anthesis; disc florets conspicuously white, yellow, pale yellow, or purple; florets mainly bisexual; female florets > 12 per head (except 2-8 in Polymnia and 8-15 in Verbesina occidentalis).
                                                      26 Leaves strongly basally disposed, the basal-most leaves sitting almost flat on the ground and overlapping; disc flowers maroon-purple
                                                      26 Leaves mainly or strictly cauline (not basally disposed); disc flowers white, yellow, or reddish-brown.
(c) Horn, Jay
                                                          28 Involucre of phyllaries not subtended by a calyculus (phyllaries sometimes in 2+ series, but without obvious calyculi below).
                                                              30 Plants primarily prostrate or trailing, sometimes erect; heads with or without ray florets; [habitats various, widespread natives and non-natives]
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Key to Asteraceae, Key C: herbaceous composites with opposite leaves and radiate heads

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1 Ray florets white, pink, or purple (rarely pale yellow or lavender).
  2 Ray floret (the lamina) persistent on the achene and becoming papery and bleached
  2 Ray floret (the lamina) articulate from the achene and falling, thus the mature heads not appearing papery.
© Scott Ward
    3 Pappus of a minute crown (coroniform); disc florets white or whitish.
    3 Pappus not only coroniform, either absent or variously composed of scales, awns, or plumose bristles (Galinsogeopsis has 2 antrorsely barbed bristles plus a crowns of laciniate scales); disk florets yellow, red-brown, or pinkish.
(c) Hill, Sonnia
      4 Heads with an involucre not subtended by a calyculus.
(c) Hill, Sonnia
        5 Rays pink, the laminae 5-14 mm long; [OK and TX westward; subtribe Cheaenactidinae]
        5 Rays white or whitish-yellow; the laminae shorter, typically < 5 mm long (occasionally longer in Polymnia).
          6 Plants larger, 50-150+ cm tall; perennials; leaves > 10 cm long, sometimes with winged petioles or clasping basal appendages; disc florets functionally staminate; [natives of higher-quality, limestone or novaculite habitats; subtribe Polymniinae]
          6 Plants smaller, 2-40 cm tall or long (if stems > 40 cm then plants usually procumbent or decumbent); annuals or perennials; leaves usually < 10 cm long, lacking winged petioles or clasping basal appendages; disc florets bisexual and fertile.
             7 Stems usually copiously glandular-pubescent; leaf blades cordate to subdeltate or usually strongly 3-lobed (but not pinnate), the margins singly or doubly crenate; disc florets 40-100+; plants erect to decumbent; [native, s. TX westward; subtribe Peritylinae]
             7 Stems not copiously glandular-pubescent; leaf blades lanceolate to broadly ovate or deltate, or pinnately to palmately lobed (Tridax); plants erect or ascending to procumbent (Tridax]; [non-natives of disturbed habitats, widespread; subtribe Galinsoginae].
               8 Plants with leaves simple, unlobed; pappus either absent or of 5-20 laciniate or fimbriate scales; plants annual, erect
               8 Plants usually with a mix of simple and 3-lobed leaves; pappus usually of ca. 20 plumose (or setiform) scales; plants perennial, usually at least somewhat procumbent
      4 Heads with an involucre subtended by a calyculus of bracts (these often but not always reflexed); the phyllaries often appearing somewhat translucent or of a distinctly different color, shape, or texture from the leafy colored bracts below; [tribe Heliantheae; subtribe Coreopsidinae].
                 9 Phyllaries connate for at least ¼ their length; heads with or without ray florets; [MS westwards in our area]
                 9 Phyllaries distinct; heads with ray florets; [collectively widespread in our area].
                   10 Cypselas beaked, not strongly flattened, 7-30 mm long, with 1 groove per face; leaves highly dissected
                   10 Cypselas beakless, more or less strongly flattened and also often winged, 1.2-16 mm long, with 0 or 2 grooves per face; leaves simple to highly dissected.
                     11 Cypselas 2.5-16 mm long, usually not winged; pappus awns (if present) usually retrorsely barbed; rays white
                     11 Cypselas 1.2-4 mm long, winged (C. nudata) or not (C. rosea); pappus awns (if present) barbless; rays pink, purple, or white
1 Rays predominantly yellow, orange, or red (sometimes with some brown, maroon, or purple coloration as well).
                          13 Leaves and phyllaries with large, scattered, embedded oil glands, making the plants strongly aromatic (the glands translucent in living plants, usually golden-brown or blackish in herbarium specimens); plants annual, decumbent and much branched from the base (except Tagetes, annual and generally erect and sparingly branched); [tribe Heliantheae; subtribe Pectidinae].
                            14 Leaves pinnately lobed or pinnatisect (pinnately divided nearly to the midrib but the leaflets not separate), the margins of terminal segments usually serrate (sometimes entire).
                                  17 Phyllaries distinct to their bases, or nearly so; ray florets 5-8; heads borne singly or in pairs/triplets; leaf surfaces puberulent
                          13 Leaves and phyllaries lacking embedded oil glands, though smaller punctate glands sometimes present; perennial or annual plants, upright and little or moderately branched below the inflorescence.
                                       19 Leaves mainly basal or basally disposed (a few pairs low on the stem), the blades elliptic to ovate, the surfaces hirsute and stipate-glandular
                                         20 Pappus absent, of scales, or coroniform (if coroniform then with 6-8 barbellulate bristles as in Jamesianthus); leaf blades unlobed; collectively widespread, including c. TX]
                                           21 Heads smaller and many (10-300+), arranged into dense, flat-topped corymbs; disc florets 1-15; ray florets 0-2, the laminae inconspicuous; phyllaries 6 (-9), in 1 series; [collectively more widespread but absent from n. AL and wc. GA]
                                           21 Heads larger and fewer (< 9 per inflorescence), arranged singly or in loose corymbs; ray florets 6-14, the laminae conspicuous; phyllaries 12-18, broadly ovate, squarrose and in several imbricate series; [on calcareous substrates in n. AL and wc. GA]
(c) Ward, Scott G
                                             22 Disc florets functionally staminate (“sterile”, not producing cypselae), the style undivided, their ovaries much smaller than ovaries of the ray florets (which are functionally pistillate).
(c) Tathagath, Swarochi - CC-BY
                                               23 Inner phyllaries prickly with straight or uncinate prickles, and each enveloping a cypsela and swelling into a bur-like structure
                                               23 Inner phyllaries unarmed, not becoming bur-like (though those of Melampodium do invest the fruit).
                                                 24 Plants with tack-glands or pit-glands on stems, leaves, and/or phyllaries; [waif, e. TX; native further westward]
                                                        27 Plants perennial, often trailing; pappus persistent, forming a minute, half-cup-shaped crown; [e. LA eastward, e. of MS river]
(c) Cressler, Alan M.
                                                      26 Taller, robust plants, the stems usually 5-40 cm long at maturity, erect; pappus absent or of 2 awns.
                                             22 Disc florets functionally bisexual (“fertile”, producing cypselae), the style divided, their ovaries as large as, or larger than, ovaries of the ray florets (which may be either functionally pistillate or completely neuter).
                                                                       34 Paleae not notably clasping the cypsela; cypselae notably flattened (or weakly compressed/angled in Guizotia); heads small, the receptacle 3-8 mm in diameter (ca. 10-15 mm in Guizotia).
                                                                           36 Cypselae of the rays and discs similar, monomorphic and not as above (the achenes weakly dimorphic in C. vialis, but the apical awns of similar length and the margins with only small, inconspicuous winglike projections)
                                                                       34 Paleae either entirely enveloping and falling with each cypsela or conduplicate (V-shaped in cross section), the 2 sides of the V partially clasping the cypsela; cypselae flattened, terete, or angled; heads mostly larger.
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
                                                                              37 Phyllaries apparently 4, the outer 4 foliaceous and forming a fused quadrangle which conceals the much smaller and narrower inner phyllaries (each inner phyllary subtending a ray floret); cypselae finely 32-40 ribbed
                                                                              37 Phyllaries not as above, instead 5 or more and not forming a conspicuously fused quandrangle; cypselae angled or smooth (sometimes angled, but lacking many fine ribs)
                                                                                  39 Disc florets without hairy staminal filaments; pappus absent or of 2-3 scales or awns (sometimes accompanied by up to 8-12 additional shorter scales in Helianthus and Simsia, but these readily falling); [collectively widespread].
                                                                                                 46 Leaf blades usually broader (if linear, leaves either whorled or pappus present); plants annual or perennial, with or without woody caudices; pappus typically of scales or awns; [collectively widespread in our flora area].
                                                                                                   47 Leaves linear, lanceolate, or ovate, almost always some leaves on a plant > 7 mm wide; plants from crowns, some species with thickened vertical storage roots (only H. tuberosus producing horizontal tubers); [collectively widespread in our area]
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Key to Asteraceae, Key D: Herbaceous composites with the leaves basal only (stems bearing heads with bracts only)

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(c) Cressler, Alan M.
1 Heads quasi-radiate (corollas of flowers bilaterally symmetrical); [natives, of the Coastal Plain]; [tribe Mutisieae]
  2 Lower leaf surfaces finely hirtellous and stipitate-glandular; [TX]
(c) Keith, Eric - CC-BY-NC, permission granted to NCBG
  2 Lower leaf surfaces densely covered with dense wool; [Coastal Plain, NC to FL, west to TX]
(c) Murashkin, Stanislav - CC-BY
(c) Bradley, Keith
(c) Cressler, Alan M.
1 Heads either radiate (with ray and disc flowers), disciform (with outer pistillate flowers barely radiate, the subligulate portion ca. 0.5 mm long, and inner disc flowers, or discoid (with disc flowers only)
(c) Bradley, Keith
    3 Heads disciform; involucres 2-4 mm in diameter; [natives, of s. FL]; [tribe Plucheae]
    3 Heads discoid or radiate; involucres 10-20 mm in diameter; [non-natives, more common northwards and inland]; [tribe Senecioneae].
(c) Murashkin, Stanislav - CC-BY
      4 Heads discoid, disc flowers purplish; heads borne in a raceme or thyrse on a leafless stem, before the leaves
(c) Cressler, Alan M.
      4 Heads radiate, rays yellow, disc flowers yellow; heads borne solitary on scapes, before the leaves
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Key to Asteraceae, Key E: herbaceous composites with leaves alternate or basal,
liguliflorous heads (composed of ligulate florets), and sap usually milky

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1 Cypselae (at least of the inner florets of the head) beaked, the beak usually > ½ the length of the cypselae body.
  2 Heads solitary and terminal at the end of a stem unbranched to its base.
    3 Flower color pink to purple or white
    3 Flower color yellow to yellowish-white.
      4 Leaves basal and cauline, grasslike (untoothed and unlobed); stem leafy
      4 Leaves basal only, variously toothed to pinnately lobed; stem scapiform (leafless).
(c) Fleming, Gary P.
        5 Pappus of bristles
(c) Zharkikh, Andrey - CC-BY-NC, permission granted to NCBG
(c) Jauch, Wolfgang - CC-BY
        5 Pappus either of outer scales and inner bristles or entirely of aristate scales.
(c) Jauch, Wolfgang - CC-BY
          6 Pappus of outer scales and inner plumose bristles; leaves oblanceolate to oblong; plants annual or perennial
(c) Zharkikh, Andrey - CC-BY-NC, permission granted to NCBG
          6 Pappus of aristate scales; leaves linear to narrowly lanceolate; plants annual
  2 Heads several per stem, in various corymbiform, umbelliform, spiciform, or paniculiform arrays (rarely solitary and terminal in the smallest and most depauperate individuals in a population.
                 9 Plants taprooted annuals or biennials, without rhizomes
                 9 Plants rhizomatous perennials, the rhizomes deeply rooted in the substrate
                   10 Pappus of plumose bristles, at least the inner series; plant an annual or biennial.
                   10 Pappus of simple capillary bristles; plant an annual, biennial, or perennial.
(c) Wright, Janet - CC-BY-NC, permission granted to NCBG
© Scott Ward
                       12 Beak of the cypsela with a ring of soft white reflexed hairs at the summit (just below the pappus); phyllary apices usually with keel-like flap
                       12 Beak of the cypsela lacking a ring of hairs as described; phyllary apices lacking keel (phyllary bases can be keeled in Crepis)
                          13 Pappus either of 40-50 (or more) smooth bristles or of 20-30 barbellulate bristles; plant a perennial.
1 Cypselae beakless, the apex typically rounded or truncate (sometimes tapered but lacking a distinct beak and conspicuously < ½ the length of cypselae body).
                              15 Leaves basally disposed (stem leaves few or none, if present generally smaller in size than the basal leaves, which are persistent into flowering and fruiting); corollas yellow, orange, or red.
                                  17 Heads solitary or 2-3; pappus absent, the cypselae never bearing scales or bristles; cypselae with 8-10 ribs (3-5 prominent); [waif, ne. US]
                                  17 Heads solitary; pappus present (occasionally absent in Krigia); cypselae with 10-20 ribs; [widespread natives]
                                    18 Pappus of 40-80 smooth to barbellulate bristles and sometimes a few subulate to setiform scales (but pappus never absent); [Great Plains, midwest US]
                                             22 Flowers usually yellow to orange; [widespread, including TX; tribe Cichorieae].
                                               23 Involucre 3-5 mm high; achenes 1.5-2.5 mm long; pappus bristles basally connate (unified basally into a ring-like structure at the junction of achene summit), 2.5-3.5 mm long
                              15 Leaves basal and cauline (plant often beginning with a basal rosette, but by flowering bearing well-developed stem leaves about as large as the basal leaves, the basal rosette often withering prior to flowering and fruiting); corollas yellow, orange, red, blue, pink, white, or lavender.
                                                          28 Cypselae 1.2-2.8 mm long; heads borne single at the ends of scapiform stems that are unbranched (rarely few-branched near the base); plants to 7 dm tall
                                                                   32 Leaves linear, entire, < 3 mm wide, or reduced to scales; cypselae 11-14 mm long; [of the Coastal Plain of GA and se. AL south to s. FL]
                                                                   32 Leaves broader, of various shapes, usually hastate, irregularly lobed, and/or serrate; cypselae 3.5-10 mm long; [collectively widespread in our area, south to n. FL]
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Key to Asteraceae, Key F: herbaceous composites with leaves spiny, leaves alternate or basal, and heads discoid

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1 Heads appearing spherical (the ‘visual head’ actually a secondary head aggregated of numerous 1-flowered heads); disk flowers blue (rarely almost white)
1 Heads not spherical; disk flowers pink (rarely yellow).
  2 Stem winged, the wings armed with spines.
      4 Cypselas borne on the surface of the receptacle, intermixed with setiform scales; foliage glabrous or more loosely and sparsely pubescent
      4 Cypselas borne in the pits of the naked honeycombed receptacle; foliage densely white-tomentose
  2 Stem not winged.
        5 Leaves green with white mottles
        5 Leaves green (or relatively uniformly whitened by hairs, especially on the lower surface).
          6 Disc flowers pink (rarely white)
          6 Disc flowers yellow to maroon .
               8 Inner phyllaries tipped with small, simple spines; cypselas 4-angled; receptacles epaleate but bearing subulate scales; pappus absent or of narrow scales 1-10 mm long
               8 Inner phyllaries tipped by pinnately divided spines > 5 mm long; cypselas terete, 20-ribbed; receptacles epaleate but bearing flattened bristles; pappus of 2 series of smooth or roughened awns, the outer series 9-10 mm long, the inner 2-5 mm long
                 9 Heads radiate, the laminae broad and yellow-colored; leaves toothed with small spines present; [tribe Astereae].
                   10 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)
                   10 Phyllaries not spine-tipped and lacking conspicuous white margins, 0.9-1.7 mm wide.
                 9 Heads discoid (Carlina with inner phyllary tips stramineous, and reminiscent of ray laminae); leaves with prominent, sharp spines; [tribe Cardueae].
                     11 Receptacle epaleate but scaly, each flower surrounded by connatemembranous scales, dissected upwards into linear lobes
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Key to Asteraceae, Key G: Herbaceous composites with the leaves alternate, the heads lacking rays, and with 0 pappus

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1 Receptacle paleate (bearing receptacular bracts which individually subtend at least some of the flowers of the head).
  2 Involucres absent or vestigial, usually with 0 phyllaries; heads very small, < 6 mm high, < 4 mm wide; annuals, < 4 dm tall; disc corollas hidden or dingy in color; [tribe Gnaphalieae]
    3 Bisexual flowers (1-) 2-10 (-11), pappus of (11-) 13-28+ bristles visible in heads; functionally staminate flowers 0.
      4 Receptacles cylindric to clavate (5-15× as tall as the diameter); most pistillate paleae open to ± folded (at most each enfolding, not enclosing a floret; apices acuminate to aristate); innermost paleae erect to ascending in fruit; cypselae mono- morphic (the outer ± equaling the inner)
      4 Receptacles fungiform to obovoid (0.4-1.6× as tall as the diameter); most pistillate paleae ± saccate, each ± enclosing a floret, apices blunt; innermost paleae spreading in fruit; cypselae dimorphic (the outer longer than the inner)
    3 Bisexual flowers 0 or 2-7, pappi 0; functionally staminate flowers 0 or 2-5, pappi 0 or of 1-10 (-13) bristles hidden in heads
        5 Paleae of the bisexual or staminate flowers flat to concave, not enclosing florets, apices entire; cypselae glabrous; [mainly west of the Mississippi River, rarely east (as in MS, AL, GA, and SC]
        5 Paleae of the bisexual flowers saccate, each enclosing a floret, apices 2-fid or 3-fid; cypselae (at least the outer) strigose; [se. Texas]
  2 Involucres present, conspicuous, of many phyllaries; heads larger, 2-20+ mm wide; perennials or coarse annuals, 2-25 dm tall; disc corollas apparent, yellow, white, or pink to purplish.
          6 Disc flowers yellow or greenish yellow; [either native of s. TX southwards, or a waif]
          6 Disc flowers white or whitish to pink or purple; [collectively widespread].
               8 Heads in corymbiform arrays; heads bisexual; involucres not burlike or nutlike, lacking tubercles or hooked or straight prickles or spines; leaves lanceolate, unlobed, cuneate at base
                 9 Heads lacking ray flowers; disc flowers pink (rarely nearly white); [Coastal Plain; FL and GA]
                 9 Heads with 5 white (fading to cream), scoop-shaped, inconspicuous ray flowers (keyed here as a 'failsafe'); disc flowers white; [widespread in our region]
               8 Heads in spiciform or racemiform arrays; heads unisexual (each head either with only female or only male flowers); involucres burlike, with tubercles or straight or hooked spines or prickles; leaves ovate or broader (in outline), often pinnatifid or bipinnatifid, truncate, cordate, or cuneate at base; [collectively widespread in our region].
                   10 Involucres of pistillate heads (burs) 1-4 mm long, with (1-) 5-12+ straight spines; larger leaves bipinnatifid
                   10 Involucres of pistillate heads (burs) 10-40 mm long, with 30-75+ hooked prickles; phyllaries larger leaves pinnatifid or unlobed
1 Receptacle epaleate (lacking receptacular bracts individually subtending flowers, but the receptacle sometimes bearing bristles, setae, hairs, or pits with laciniate margins.
                     11 Flowers white, pink, purple, or bluish.
                       12 Annuals, (1-) 2-10 (-30+) cm tall; corollas whitish, inconspicuous, absent on most of the (pistillate) flowers; leaves 2-3× pinnati-palmately lobed into linear segments; cypselae with an apical spine
                       12 Perennials, 10-150 cm tall; corollas at least light pink and often darker pink, purple, or blue, conspicuous, present on all flowers; leaves pinnately lobed or entire, the segments not linear; cypselae not spined.
                          13 Heads ovoid, 10-21 mm long; flowers 15-40 mm long, with long, narrow lobes; phyllaries >30, in 6+ series, and the apices often with a fringe of appendages and/or a spine tip; basal and lower stem leaves usually pinnately lobed (to entire and unlobed); [widespread in our region, especially northwards]
                          13 Heads cylindrical, 2-6 mm long; flowers ca. 3 mm long, with deltate lobes; phyllaries 12-15 in 2-3 series, herbaceous and unadorned; basal and lower stem leaves entire and unlobed; [Coastal Plain of FL and GA]
                     11 Flowers yellow, cream, or rarely red-tinged.
                              15 Heads 3-4 (-6) mm in diameter, solitary; plants 0.3-3 dm tall; [ballast waif, especially in wet, saline places]
                              15 Heads (3-) 5-20+ mm in diameter, solitary or borne in corymbiform or paniculiform arrays; plants 1.5-15 dm tall.
                                    18 Disc corollas greenish yellow, 1.1-1.3 mm long; fresh plants pineapple-scented; [common weed, especially northwards in our region]
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Key to Asteraceae, Key H: Herbaceous composites with the leaves alternate, the heads lacking rays, and with a pappus of bristles only

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1 Receptacle paleate (bearing receptacular bracts which individually subtend at least some of the flowers of the head).
  2 Involucres absent or vestigial, usually with 0 phyllaries; heads very small, < 6 mm high, < 4 mm wide; annuals, < 4 dm tall; disc corollas hidden or dingy in color; [tribe Gnaphalieae].
    3 Receptacles cylindric to clavate (5-15× as tall as the diameter); most paleae of pistillate flowers open to ± folded (at most each enfolding, not enclosing a floret; apices acuminate to aristate); innermost paleae erect to ascending in fruit; cypselae monomorphic (the outer ± equaling the inner)
    3 Receptacles obovoid (0.4-1.6× as tall as the diameter); most paleae of pistillate flowers ± saccate, each ± enclosing a floret, apices blunt; innermost paleae spreading in fruit; cypselae dimorphic (the outer longer than the inner)
  2 Involucres present, conspicuous, of many phyllaries; heads larger, 2-20+ mm wide; perennials or coarse annuals, 2-25 dm tall; disc corollas apparent, white, or pink to purplish or reddish.
      4 Phyllaries tipped by a hooked spine
        5 Cypselae with 5 angles or 5 grooves; involucre 2-3 mm tall and in diameter; pappus of 1 (-5+) usually glandular setae (interpretable as bristles, hence keyed here); [Coastal Plain; FL and GA]
        5 Cypselae with 10 ribs; involucre 3.5-12 (-15) mm tall and in diameter; pappus of 35-40 barbellulate bristles; [mainly Coastal Plain; VA south to s. FL, west to e. LA]
          6 Heads larger, the involucre 6-15 mm high, with 15-40 phyllaries; leaves with conspicuous (at least at 10× magnification) resin dots.
          6 Heads smaller, the involucre 3.5-6 mm high, with 5-12 phyllaries; leaves without shining punctate glands (except punctate-glandular in Litrisa carnosa, of the FL peninsula).
             7 Stem eglandular, glabrous or spreading-hirsute; peduncles glabrous or stipitate-glandular; pappus bristles in 1 series; [widespread in the Coastal Plain].
1 Receptacle epaleate (lacking receptacular bracts individually subtending flowers, but the receptacle sometimes bearing bristles, setae, hairs, or pits with laciniate margins; some taxa lacking paleae on many or most flowers of the head are keyed here as well, as a failsafe).
(c) Gwaltney, John
               8 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, except in species in which the phyllaries are radially winged); calyculus (of bracts subtending the phyllaries and differing from them in texture, color, or orientation) present or not; [tribe Senecioneae]
                 9 Annuals, 2-10 dm tall (or perennial, vining or sprawling and to 30 dm long in Gynura); leaves cauline and alternate; disc flowers orangey-brown, brick-red, purplish, yellow.
                   10 Plants annual, upright or ascending, not purple-hairy.
                 9 Perennials (robust annuals in Erechtites), 2-30 dm tall; leaves basally disposed and alternate on the stem (except only alternate in Erechtites); disc flowers cream or yellow (rarely pale lavender in Arnoglossum).
                       12 Plants annual, with leaves primarily on the stem; leaves sharply and raggedly toothed or even pinnately lobed; heads disciform (the outer flowers female, the middle bisexual, and the inner functionally male)
                       12 Plants perennial, with leaves basally disposed (larger basal leaves, decreasing in size upwards, the basal leaves sometimes withering late in the year); leaves with generally regular toothing, stem leaves sometimes pinnately lobed; heads discoid (all flowers bisexual)
                            14 Perennials; leaves basally disposed, the basal or lower stem leaves unlobed (though toothed)
                            14 Annuals; leaves not basally disposed, evenly distributed on the stem, the lower stem leaves more-or-less pinnatifid
                          13 Disc flowers cream, white, or greenish white (to pale lavender in some Arnoglossum).
(c) Ward, Scott G
                              15 Phyllaries 5, radially wing-keeled or not; disc flowers 5; calyculus absent
                              15 Phyllaries 7-21, not radially winged; disc flowers 10-55 (-80+); calyculus absent or of 1-9+ bracts.
                                16 Plants (5-) 6-24 dm tall; calyculus of 4-9+ bracts; [collectively relatively widespread in our region]
                                16 Plants 1-7 dm tall; calyculus absent or of 1-5+ bracts; [Mountains of w. NC and e. TN]
               8 Phyllaries in 3-17 series and unequal in length (imbricated); calyculus absent.
                                  17 Stem not winged (sometimes the leaves decurrent < 2 cm down the stem from the node).
                                       19 Plants perennial, mat-forming by stolons, with basal rosettes of spatulate leaves, these usually with obvious appressed hairiness on (at least) the lower and (sometimes also) the upper blade surfaces; erect stems (with scattered alternate leaves) 4-45 cm tall; plants usually dioecious (pistillate and staminate heads on separate plants)
                                       19 Plants annual, biennial, or perennial, not mat-forming or stoloniferous, erect, the leaves usually lanceolate or linear (spatulate in some species), leaf surface hairiness variable; erect stems (with alternate leaves) 5-80 cm tall; plants hermaphroditic (with heads containing both pistillate and functionally staminate flowers) or dioecious or subdioecious (in Anaphalis).
                                         20 Plants annuals (perennials in Omalotheca sylvatica); heads disciform (each bisexual); plants hermaphroditic.
                                           21 Leaves various in shape, the lager > 4 mm wide, acuminate, acute, obtuse or rounded at the tip; pappus readily falling, the bristles barbellate to barbellulate.
                                             22 Heads in capitate clusters arrayed in corymbiform or paniculiform arrays; phyllaries white or silvery; pappus bristles distinct, falling individually
                                             22 Heads in spicate arrays, or in glomerules axillary to leaves or well-developed bracts; phyllaries white to red-tinged or brown; pappus connate at the base into a ring, falling as a unit.
                                                              30 Plants dioecious, either male or female; heads either staminate, with 10-50 flowers, or pistillate, with 20-150 flowers; heads pale yellow to white
                                                              30 Plants hermaphroditic; heads bisexual, with 2-35 flowers, either all perfect (bisexual), or a mixture of perfect (bisexual) and functionally staminate flowers.; heads yellow to pale yellow.
                                                                       34 Phyllaries either spine-tipped, or appendaged with a marginal zone that is strikingly different in color and texture than the phyllary body (except Leuzea); receptacle epaleate, but densely beset with bristles or subulate scales (flattened bristles).
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Key to Asteraceae, Key I: Herbaceous composites with the leaves alternate, the heads lacking rays, and with a pappus wholly or partly of scales or awns

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1 Disc flowers yellow, orange, red, or brownish.
(c) cuamo, liaska - CC-BY
  2 Leaves 1-2× pinnately lobed into linear or filiform segments.
(c) Ward, Scott G - CC-BY
(c) Shaw, Joey
  2 Leaves unlobed, or if pinnately lobed, the segments broad (> 3 mm wide).
(c) Ward, Scott G
      4 Receptacle paleate
          6 Phyllaries 25-125 in 3-9 series; receptacles flat or slightly convex
1 Disc flowers pink, purple, or white
(c) Cressler, Alan M.
(c) Ward, Scott G - CC-BY
               8 Receptacle epaleate.
                 9 Disc flowers 1-5 (rarely more) per head.
(c) Kieschnick, Sam - CC-BY
                   10 Disc flowers white (rarely cream), 3; heads not aggregated into a secondary cluster subtended by bracts; [se. TX]
                   10 Disc flowers lavender to purple, sometimes so lightly so as to be white, 1-4 (-5+); heads aggregated into clusters of 1-40 heads, subtended by 1-3 bracts; [collectively widespread in our region]
(c) Keim, Mary - CC-BY-NC-SA, permission granted to NCBG
                     11 Heads (1-) 10-40 per secondary cluster, borne in corymbiform arrays; bracts subtending clusters (2-) 3, deltate; pappus of 5 (-6) scales, each aristate
(c) Horn, Jay - CC-BY
                     11 Heads 1-5+ per secondary cluster, borne in spiciform arrays; bracts subtending clusters 1-2, linear, lanceolate, or spatulate; pappus of 6-10 scales, laciniate or aristate
(c) Cressler, Alan M.
                 9 Disc flowers (2-) 10-100+ per head (at least most heads with >10 flowers).
                          13 Involucres 2-3 mm in diameter; flowers 7-10 per head; [Coastal Plain, FL and GA]
                          13 Involucres 4-15+ mm in diameter; flowers 20-80 per head; [SC, GA, and FL westwards]
                            14 Phyllary tips modified into a spine or into an enlarged, lacerate or pectinate network or fringe; receptacle epaleate, but densely bristly; [tribe Cynareae].
                                16 Pappus normally of plumose bristles (and keyed elsewhere), but sometimes reduced to scales or awns
                              15 Heads disciform or radiant, the outer flowers of the head sterile, with long lobes, appearing like false rays
                                  17 Plant a perennial; flowers pink to purple, flowering Jun-Oct
                                  17 Plant an annual; flowers pale to medium blue, flowering Apr-Jun
                            14 Phyllary tips not so modified, unarmed and unelaborate; receptacle epaleate and naked; [tribe Vernonieae].
                                    18 Peripheral flowers of the heads enlarged and bilaterally symmetrical, appearing like "false rays"
                                    18 Peripheral flowers of the heads similar to the interior flowers, all disc flowers.
(c) Pietruszewski, Jacek - CC-BY
                                         20 Heads each subtended by 3-8 leafy bracts; pappus of narrow scales only, quickly falling
© Scott Ward
                                         20 Heads not subtended by leafy bracts; pappus of an inner series of scales or bristles and an outer series of bristles, persistent
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Key to Asteraceae, Key J: Herbaceous composites with the leaves alternate or basal and the heads radiate, the rays yellow, orange, red

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1 Disc florets functionally staminate (sterile), with style undivided.
  2 Phyllaries 10 or less, in 2 series; plants annual; [primarily OK and TX]
  2 Phyllaries 12 or more, in (2-) 3-4 series; plants perennial; [collectively widespread, including OK and TX in our area]
(c) Ward, Scott G
    3 Cypselae with broad wings with 2 confluent awns
    3 Cypselae not winged, pappus absent or of 2-4 ciliate scales.
      4 Disc florets green, red, or maroon; pappus absent; leaves lanceolate, lyrate, or lyrate-pinnatifid (but not deeply pinnatifid); [nc. TX westward]
      4 Disc florets primarily yellow; pappus of 2-4 ciliate scales; leaves deeply pinnatifid [sw. AR and e. TX westward, waif in e. LA]
1 Disc florets bisexual (fertile), with style bifurcate.
        5 Leaves decurrent down the stem (the stem appearing winged); cypselae strongly flattened and often winged
        5 Leaves not decurrent; cypselae moderately compressed to 4-angled, not winged (or if winged, the cypselae obcompressed or obconic).
© Scott Ward
(c) Ward, Scott G - CC-BY
          6 Receptacular bracts connate to form a honeycomb-like structure in which the flowers are set; pappus of 7-12 scales
          6 Receptacular bracts not fused and not forming a honeycomb-like structure; pappus absent, of awns/scales, or a fused crown (Phoebanthus sometimes with up to 4 additional scales shorter than 2 primary lacerate scales).
             7 Heads subtended by a calyculus (bracts distinct from phyllaries)
             7 Heads without a calyculus.
               8 Leaves not noticeably clasping the stem.
                 9 Leaves pinnately lobed, the primary lobes usually pectinately divided; [non-native]
                   10 Pappus absent, or of 1-2 lacerate scales (on shoulders of cypselae) plus additional lacerate (bristlelike) scales; receptacles subspheric, conical, columnar, or otherwise convex.
                       12 Leaf blades linear; plants from slender, horizontal tubers; pappus absent or of 1-2 lacerate scales (on shoulders of cypselae) plus additional lacerate (bristlelike) scales; [natives of AL and FL; subtribe Ecliptinae]
                       12 Leaf blades variously shaped, not all linear (often with some ovate or rhombic leaves); plants from woody caudices; pappus absent; [waif in SC, native in arid southwest; subtribe Helianthinae]
                     11 Receptacle strongly conic or columnar; phyllaries 3-21, in 1-2 series; [subtribe Rudbeckiinae].
                          13 Phyllary series unequal (outer longer than inner); cypselae strongly compressed; ray florets subtended by receptacular bracts
                          13 Phyllary series subequal; cypselae not strongly compressed; ray florets not subtended by receptacular bracts (only the disc flowers with bracts)
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Key to Asteraceae, Key K: Herbaceous composites with the leaves alternate or basal and the heads radiate, the rays yellow, orange, red

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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 entire or sometimes toothed, but not pinnately lobed; receptacle epaleate or sometimes with short bristles or setae
             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
                   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 glabrous, or papillate-scabrous (but not clearly gray-green in appearance); involucre 1.5-5.5 mm in diameter; plants either annuals or subshrubs; phyllaries 4-40 in 2-4 series
                       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.
                            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).
(c) Ward, Scott G - CC-BY
© Scott Ward
                                    18 Phyllaries in one series.
                                       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 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
(c) Ward, Scott G
                                                 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).
                                                            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).
                                                                 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)
                                                                   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 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].
                                                                           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)
                                                                                  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)
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Key to Asteraceae, Key L: Herbaceous composites with the leaves alternate or basal and the heads radiate, the rays white, pink, purple, and the 0 pappus

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1 Rays primarily pink or purple, not white-tinged (flowers viewed from above, adaxial surface of the rays).
(c) Pietruszewski, Jacek - CC-BY
  2 Receptacles epaleate; leaves pinnatisect; [waif, ne. US]
(c) Spaulding, Dan - CC-BY-NC, permission granted to NCBG
© Scott Ward
  2 Receptacles paleate; leaves simple or bladeless; [widespread natives]
(c) Cressler, Alan M.
(c) Spaulding, Dan - CC-BY-NC, permission granted to NCBG
    3 Leaves without blades (the petioles terete, appearing Juncus-like); ray florets pink or purplish; disc florets fewer (60-120+), the corollas usually yellowish; [wet pinelands and seepages]
(c) Bradley, Keith
© Scott Ward
    3 Leaves broad and conspicuous; ray florets purple; disc florets many (200+), the corollas pink, green, red, purple, or yellow colored; [plants of prairies and similar habitats]
(c) Hill, Sonnia
1 Rays primarily white to white-tinged or yellow throughout (lamina of the ray with at least some white basally if not uniformly yellow).
(c) Hill, Sonnia
      4 Disc florets functionally staminate (thus cypselae only forming from ray florets)
        5 Leaves entire or toothed, but not deeply pinnatisect; sometimes with smaller rounded lobes (Leucanthemum basal leaves can have deeper, round lobes); plants usually not aromatic.
          6 Stem internodes usually winged (at least proximally)
             7 Leaves primarily basal, the cauline leaves absent or fewer and much reduced in size from basal leaves; abaxial surface of the ray laminae white or sometimes pink-tinged (on live plants) but lacking a prominent colored midstripe.
               8 Leaves strigose, the margins crenate-serrate; roots not red-tipped; abaxial surface of ray laminae often pink or purple tinged, flowers closing at night
               8 Leaves glabrous (or faces sparsely hairy), the margins entire or toothed; roots usually red-tipped; rays drying pinkish but abaxial surface not conspicuously pink tinged on live plants
             7 Plants with well-developed cauline leaves, the margins entire or sometimes toothed (usually entire in Aphanostephus, occasionally deeply lobed); abaxial surface of the ray lamina sometimes white, but often with a prominent purple or blue midstripe (except Leucanthemum, which merely dries pink)
                 9 Flowering heads smaller, arranged in corymbiform or paniculiform arrays; ray florets with diminuitive laminae (0.3-5.0 mm long), heads thus sometimes superficially appearing disciform (rays sometimes double in horticultural forms as in Achillea ptarmica)
                   10 Plants aromatic; leaves linear to narrowly lanceolate, the surfaces glabrous or sparsely hairy; pales more or less folded but lacking distal papillae; cypselae not shed along with subtending phyllary and disc florets; [tribe Anthemideae]
                   10 Plants not aromatic; leaves variously shaped, at least some usually lyrate or oblanceolate (not all linear), the surfaces hairy and gland-dotted (at least abaxially); pales distally pappilate or fimbriate; cypselae shed along with subtending phyllary and 2 disc florets each invested in a pale; [tribe Heliantheae]
                 9 Flowering heads larger, singular on scapes (if in 2's or 3's, these large and not in broad corymbiform arrays), rays prominent, the laminae usually > 10 mm long
                     11 Rays white abaxially (drying pinkish); receptacles broadly convex, not pitted; plants rhizomatous perennials; pappus absent; [tribe Anthemideae]
                     11 Rays white or with prominent blue or purple midstripe (sometimes present after drying); receptacles conic, pitted; plants tap-rooted annuals (except Astranthium riddellii); pappus absent, coroniform, or of scales; [tribe Astereae]
                       12 Phyllaries scarious margined; cypselae 4-angled and with 4-12 thick ribs, pappus absent, of scales or coroniform; ray florets closing distally at night
                       12 Phyllaries sometimes hyaline but not scarious margined; cypselae compressed, lacking prominent ribs (though sometimes glochidiate), pappus absent or short coroniform; ray florets not closing at night
        5 Leaves deeply lobed or pinnatisect, the ultimate segments linear or if rounded, the sinuses of the lobes nearly reaching the midrib (pinnatifid); plants typically aromatic (except Tripleurospermum and Parthenium); [tribe Anthemideae].
                          13 Receptacles paleate (chaffy or with apparent bracts), the pales sometimes distally fimbriate or papillate (Parthenium).
                              15 Rays primarily white to white-tinged (without strong yellow color at the base of the laminae) or yellow throughout (lamina of the ray with at least some white basally; if rays are white).
                                16 Flowering heads smaller, arranged in corymbiform or paniculiform arrays; ray florets with diminuitive laminae (0.3-5.0 mm long); ray and disc florets both white or white-ish.
                                  17 Plants usually aromatic; pales more or less folded but not distally fimbriate or papillate; cypselae not shed along with phyllary and disc florets; [tribe Anthemideae]
                                  17 Plants not aromatic (at least not conspicuously so); pales distally fimbriate or papillate; cypselae shed along with subtending phyllary and 2 disc florets each invested in a pale; [tribe Heliantheae]
                                16 Flowering heads larger, arranged mostly singular at the ends of scapes, not in broad corymbiform arrays (except Tripleurospermum, which has larger heads and prominent rays), ray laminae prominent; ray and disc florets differing in color (rays typically white; discs typically yellow).
                                    18 Plants annual, erect or decumbent, ill-scented or not; ultimate leaf margins dentate to lobed; cypsela ribs usually 9-10 (sometimes lacking); [widespread non-natives]
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Key to Asteraceae, Key M: Herbaceous composites with the leaves alternate or basal and the heads radiate, the rays white, pink, purple, and with a pappus of bristles only

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1 Head 1 per plant (individual rosette); stems 0.1-0.3 dm tall; [TX and OK westwards]
1 Heads 5-300+ per (well-developed) plant; stems 0.3-35 dm tall; [collectively widespread].
  2 Stems with numerous thorns (1-2 cm long, modified axillary branches), and few or no leaves
  2 Stems leafy, not armed with thorns.
    3 Leaves unlobed; plant perennial from caudices, crowns, or rhizomes.
      4 Annuals from taproots; ray florets 0.3-7 mm long.
        5 Ray laminae 0.3-1.0 mm long; cypselas 1.0-1.5 mm long, compressed, 1-nerved on each face
        5 Ray laminae 1.3-7 mm long; cypselas (1.2-) 1.5-2.7 (-3) mm long, compressed or not, 5-18-nerved.
          6 Disc flowers 25-35 per head; ray flowers in 1 series
      4 Perennials from caudices, crowns, or rhizomes; ray florets > 3 mm long.
             7 Basal and lower stem leaves petiolate, with blades cordate to rounded at the base
               8 Heads borne in corymbiform arrays, the branches often subtended by large and leaf-like bracts; phyllaries < 2.5 (-3)× as long as wide, often > 1 mm wide; plants (in most species) colonial by rhizomes; rays (in most species) white; phyllaries (in many species) glandular
               8 Heads borne in paniculiform arrays, the branches bearing small and narrow bracts; phyllaries > 3× as long as wide, often < 1 mm wide; plants (in most species) solitary; rays (in most species) blue, violet, or pink; phyllaries eglandular
             7 Basal and lower stem leaves sessile (sometimes cordate-clasping), or if petiolate then with cuneate to attenuate bases.
                 9 Rays pink, purple, lavender, blue, or pale pink [plants with pale pink rays may need to be keyed both ways].
                   10 Heads borne either in flat-topped or rounded, corymbose arrays, or in narrow racemiform or spiciform panicles, or solitary.
                     11 Leaves 1.2-4.0 cm long, 1-4 mm wide, stiff, scabrous margined and weakly spine-tipped; plants 1-7 dm tall; pappus in 2 series, the inner much longer than the outer (ca. 1 mm long) bristles
                     11 Leaves either longer or broader or both, herbaceous; Leaves (5-) 13-45 mm wide, herbaceous, neither scabrous-margined nor spine-tipped; plants 4-30 dm tall; pappus not divided into distinct inner and outer series.
                       12 Plants 10-35 dm tall; larger leaves (basal or low on the stem) with cuneate or attenuate bases, the blades 30-50 cm long; [non-native, rarely persistent or spreading from horticultural use]
                       12 Plants 1-12 dm tall; larger leaves with blades 2-20 cm long; [natives, collectively widespread and common in our region]
                 9 Rays white (or very slightly pink-flushed).
                          13 Heads borne either in flat-topped or rounded, corymbose arrays, or in narrow racemiform/spiciform panicles, or solitary.
                                16 Disc flowers yellow (and often fading to pink or purplish).
                                  17 Rays 2-7, the ray ligules 2-11 mm long, often twisted or contorted; phyllaries whitish with a distinct green tip, the green area about as wide as long
                                  17 Rays (8-) 9-40, the ray ligules 4-20 mm long, generally planar (or neatly coiling at post-maturity); phyllaries various.
                                    18 Pappus not divided into distinctively different outer and inner series; leaves toothed or entire.
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Key to Asteraceae, Key N: Herbaceous composites with the leaves alternate or basal and the heads radiate, the rays white, pink, purple, and the pappus absent or essentially so

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1 Receptacles paleate (with chaff); [tribe Heliantheae].
  2 Stems not winged; leaves simple; disc florets and ray florets differing in color
  2 Stems usually winged; leaves simple or pinnately to palmately lobed; disc florets concolorous (of similar color) with ray florets
1 Receptacles epaleate (lacking chaff).
      4 Plants arachnose or wooly pubescent throughout; [waif, SC; tribe Arctotideae]
      4 Plants glabrous or densely viscid but not wooly tomentose throughout (if hirsuto-pilose, this usually concentrated distally).
        5 Receptacles flat or broadly conic, not conspicuously pitted; heads in corymbiform arrays; pappus a short crown; rays white, pink, or purple adaxially; [widespread non-natives, tribe Anthemideae]
        5 Receptacles conic, pitted; heads borne singly (Aphanostephus) or in loose corymbiform arrays (Egletes); rays white adaxially; [natives primarily w. of MS river; tribe Astereae].
          6 Plants aromatic, but not densely viscid, instead sometimes hairy distally; ray laminae not shorter than involucre; phyllary margins broadly scarious; pappus coroniform or a mix of variously shaped scales; [widespread w. of MS river]
          6 Plants densely viscid with stipitate-glandular trichomes; ray laminae sometimes shorter than involucre; phyllary margins scarious or not; pappus of uneven rings; [TX]
    3 Leaves entire or toothed, but neither deeply lobed nor pinnatifid.
             7 Plants 1-3 cm tall, densely pin-cushioned (pulvinate); flowering heads sessile, borne singly, conspicuously nestled within the rosette leaves and proportionately of similar size; pappus persistent, of 12-35+ setiform scales in 1 series; phyllaries in 4-6+ series
             7 Plants of various size, but not densely pin-cushioned; flowering heads borne on stems, if peduncles short the heads not conspicuously nestled within similar-sized leaf rosettes; pappus various, phyllaries in 2-6 series.
               8 Pappus of 5-40+ longer inner bristles plus shorter outer scales or setae (these sometimes falling); stems and leaves often (but not always) stipitate-glandular.
                 9 Inner barbellate bristles numerous (5-40+); stems and leaves usually glandular; plants tap-rooted, fibrous-rooted, or stoloniferous; annuals, biennials, or perennials
                 9 Inner bristles barbellate or thicker, fewer (ca. 5); stems and leaves glandular (C. asteroides) or eglandular (C. asteroides; C. belliloides); plants tap-rooted annuals
               8 Pappus primarily of awns, scales, crowns, or thickened rings (these minute, 0.1-0.8 mm long), sometimes also accompanied by shorter inner scales or bristles; stems and leaves eglandular (sometimes minutely glandular in Chaetopappa bellidifolia).
                     11 Receptacles obscurely pitted; pappus of 2-3 sclerified awns plus often with 7-12 shorter bristles or scales; [collectively widespread]
                   10 Cypsela margins not narrowly winged (4-angled in Aphanostephus but lacking marginal wings).
                       12 Receptacles conic, pitted; cypselae 4-angled; pappus of setiform to awn-tipped scales or short ciliate crowns (0.1-0.2 mm long, minute, thus requiring magnification)
                       12 Receptacles flat or slightly convex, smooth (not pitted); cypselae variously shaped but not conspicuously 4-angled; pappus of minute, thickened rings (C. bellidifolia) or erose cuplike crowns (C. imberbis)
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Key to Asteraceae, old Key J: Herbaceous composites with the leaves alternate or basal and the heads radiate, the rays white, pink, purple

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1 Receptacles chaffy (paleate).
  2 Phyllaries dry, scarious-margined.
    3 Ray florets 1-5 mm long; heads small in corymbiform arrays
    3 Ray florets > 5 mm long; heads large, terminating the branches
      4 Ray florets < 2.5 mm long; disk florets sterile, with an undivided style
      4 Ray florets > 5 mm long; disk florets fertile, with a divided style.
        5 Ray florets pink or light purple, > 15 mm long; heads single
        5 Ray florets white, 5-10 mm long; heads 20-100 in a compound corymb
1 Receptacles naked (epaleate).
               8 Leaves basal; cypselae marginally 2-ribbed; mature plants < 2 dm tall
               8 Leaves cauline (and sometimes also basal); cypselae with ± 10 ribs; mature plants > 2 dm tall
                       12 Leaves and stems not fleshy, rarely glabrous; cypselas < 1.4 mm long
                       12 Leaves and stems fleshy, mostly glabrous; cypselas > 1.4 mm long
                     11 Not taprooted and mostly perennials; ray florets > 3 mm long.
                                               23 Ray florets white to pink or blue or purple, more numerous (usually 8-30); cypselas glabrous to pubescent but not densely silky.