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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 pinnatifid to bipinnatifid; plant annual
    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
          6 Disc flowers 4-10 (-13) per head; ray flowers in 1-3 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 in paniculiform or in diffuse and irregular arrays
                   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 in paniculiform or in diffuse and irregular arrays
                          13 Heads borne either in flat-topped or rounded, corymbose arrays, or in narrow racemiform/spiciform panicles, or solitary.
                            14 Heads arrayed in 1 (or more) cylindrical thyrses
                            14 Heads borne in either narrow racemiform/spiciform panicles, or in corymbose arrays.
                              15 Heads borne in narrow racemiform/spiciform panicles
                              15 Heads borne in corymbose arrays.
                                16 Disc flowers white
                                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 double, with an outer set of bristles < 1 mm long; leaves entire
                                    18 Pappus not divided into distinctively different outer and inner series; leaves toothed or entire.
                                       19 Achenes not glandular, either glabrous or strigillose
                                       19 Achenes densely gland-dotted

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).
    3 Leaves 1-3 pinnately-lobed or pinnatifid.
      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).
                   10 Cypsela margins narrowly winged or winglike.
                     11 Receptacles obscurely pitted; pappus of 2-3 sclerified awns plus often with 7-12 shorter bristles or scales; [collectively widespread]
                     11 Receptacles smooth; pappus of 2 thin awns plus an elliptic ring of shorter awns; [s. TX]
                   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)

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
  2 Phyllaries herbaceous, not scarious on margins.
      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).
          6 Pappus absent or coroniform.
             7 Achene faces minutely glandular-glochidiate (bearing small gland-like bristles)
             7 Achene faces glabrous or short-strigose but not glandular-glochidiate.
               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
                 9 Heads solitary or 2-3 in corymbiform arrays
                 9 Heads 5-60+ in corymbiform arrays
          6 Pappus present, of bristles or scales.
                   10 Heads primarily discoid with reduced ray florets
                   10 Heads radiate with conspicuous ray florets.
                     11 Taprooted annuals; ray florets 1-7 mm long.
                       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.
                          13 Ray florets usually > 60; blooming Apr-Oct
                          13 Ray florets usually < 60; blooming late May-Nov.
                            14 Receptacles hemispheric to conic; pappus often with 2-4 awns (Boltonia) or lacking awns and coroniform (Astranthium).
                              15 Achenes not narrowly winged, the surfaces minutely glandular-glochidiate (bearing small gland-like bristles)
                              15 Achenes narrowly winged, the surfaces sometimes puberulent but not glandular-glochidiate
                            14 Receptacles flat to slightly convex; pappus lacking awns.
                                16 At least the basal and lower leaves both petiolate and cordate/subcordate at base.
                                  17 Often colonial; inflorescence corymbiform, flat-topped or rounded; outer phyllaries > 1 mm broad
                                  17 Not colonial; inflorescence paniculiform, often elongate; outer phyllaries < 1 mm broad
                                16 Basal and lower leaves not both petiolate and cordate/subcordate at base.
                                    18 Leaves sessile and auriculate or cordate-clasping
                                    18 Leaves petiolate or epetiolate but not auriculate or cordate-clasping.
                                       19 Cypselas glandular; pappus double
                                       19 Cypselas not glandular; pappus single or double or in four series.
                                         20 Leaves silvery-silky on both sides (at least when young), entire
                                         20 Leaves not silvery-silky, entire or toothed.
                                           21 Pappus double, with inner bristles distinctly longer than outer bristles.
                                             22 Leaves not rigid, veiny, lanceolate to elliptic or ovate, > 6 mm wide
                                             22 Leaves rigid, 1-nerved, linear to linear-spatulate, < 5 mm wide
                                           21 Pappus simple with all bristles often about the same length.
                                               23 Ray florets white, few (usually 3-8); cypselas densely silky
                                               23 Ray florets white to pink or blue or purple, more numerous (usually 8-30); cypselas glabrous to pubescent but not densely silky.
                                                 24 Ray florets white; involucres < 6 mm long; phyllaries < 1 mm wide
                                                 24 Ray florets white or pink to blue or purple; involucres 7-12 mm long; phyllaries usually > 1 mm wide.
image of plant
Show caption*© Scott Ward
                                                    25 Phyllaries glandular
                                                    25 Phyllaries not glandular.
                                                      26 Phyllaries long-attenuate or loose and spreading
                                                      26 Phyllaries appressed, not long-attenuate.
                                                        27 Plants coarse-hairy; lowest leaves > 5 cm wide
                                                        27 Plants glabrous to hairy; lowest leaves < 3 cm wide