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Key to Helenium

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1 Stem leaves very numerous, 0.5-2 (-4) mm wide, not decurrent on the stem or branches; taprooted annuals.
  2 Disc corollas yellow, the lobes yellow or yellow-brown; lower and basal leaves usually withered at anthesis; lower leaves usually entire (rarely toothed); basal leaves entire to toothed (rarely pinnatifid)
  2 Disc corollas yellow, the lobes (and sometimes also the upper portion of the corolla tube) purple; lower and basal leaves often persistent; lower leaves linear to ovate, entire, toothed, lobed or pinnatifid; basal leaves pinnatifid
1 Stem leaves few to numerous, at least the larger > 4 mm wide, decurrent on the stems and branches; fibrous-rooted perennials or taprooted annuals/biennials.
    3 Ray flowers absent; disc flowers with lobes (at least) brown, red, or purple
    3 Ray flowers present; disc flowers either yellow or with lobes (at least) brown, red, or purple.
      4 Ray flowers bearing a pistil and style, fertile.
        5 Plants fibrous-rooted perennials; [section Helenium].
          6 Leaves not basally disposed, the basal leaves usually absent at flowering (if present, mostly < 2 cm long), the stem leaves not progressively reduced upward; pappus scales brownish, 0.3-1.2 mm long (usually < 1 mm long); upper cauline leaves serrate (rarely entire), mostly oblanceolate, usually broadest near the midpoint or beyond it, with conspicuous lateral veins apparent on the lower surface
          6 Leaves basally disposed, the basal rosette usually present at flowering, the basal leaves > 4 cm long, larger than the progressively smaller stem leaves; pappus scales white-hyaline, 0.9-1.9 mm long (usually > 1 mm long); upper cauline leaves entire, lanceolate, usually broadest at or near the base and rather evenly tapered to the apex, lacking conspicuous lateral veins
        5 Plants tap-rooted annuals or biennials; [section Tetrodus].
             7 Involucres 6-11 (-14) mm high, 6-11 (-13) wide (excluding the ray flowers); disk corollas 4- or 5- lobed.
               8 Disc corollas 5-lobed; ray flowers 8-9, yellow or partially/wholly red; [TX]
               8 Disc corollas 4-lobed; ray flowers 10-15, yellow; [widely distributed]
             7 Involucres 4-8 mm high, 4-8 mm wide (excluding the ray flowers); disc corollas 5-lobed.
                 9 Upper leaves serrate; pappus scales (0.2-) 0.3-0.4 (-0.5) mm long
      4 Ray flowers lacking a pistil and style, sterile; [section Leptopoda].
                   10 Disc flowers with lobes (at least) brown, red, or purple.
                     11 Disc flowers predominately 4-lobed and with 4 stamens; heads 5-50 (-80) per plant; pappus scales aristate
                     11 Disc flowers 5-lobed and with 5 stamens; heads 1-20 per plant; pappus scales acute.
                       12 Heads 1-5 (-10) per plant; pappus scales 1.0-1.7 mm long; basal leaves and lower stem glabrous to sparsely hairy; [VA west and south to ne. TN, s. MS, and e. LA]
                       12 Heads 3-20 per plant; pappus scales 0.3-0.5 mm long; basal leaves and lower stem moderately to densely hairy; [AR and n. LA]
                   10 Disc flowers with lobes yellow.
                            14 Midstem leaves barely decurrent on the stem, the decurrency < 0.5 cm; basal leaves often pinnatifid (less commonly merely dentate, repand, or entire), the lower portion of the leaf not contracted so as to be petiolate in form; achene pubescent on the ribs; peduncle pubescent; basal leaves (3.0-) 4.5-8.0 (-19.0) cm long, 0.3-1.1 cm wide, averaging ca. 7-10× as long as wide
                            14 Midstem leaves decurrent on the stem, the decurrency > 2 cm , and usually extending to the next leaf down; basal leaves usually repand or entire (rarely somewhat lobed or pinnatifid), the lower portion narrowed into a petiolate form which enlarges at its base to more-or-less clasp the stem; achene glabrous, or pubescent on the ribs; peduncle pubescent or glabrous; basal leaves averaging narrower or broader in shape (see below).
                              15 Peduncle pubescent to tomentose or lanose between the uppermost leaf and the head; achene pubescent on the ribs; heads 1-4 per plant; basal leaves (2.5-) 4.0-10.5 (-18.0) cm long, (0.8-) 1.2-2.0 (-2.5) cm wide, averaging ca. 4-6× as long as wide
                              15 Peduncle glabrous or glabrate between the uppermost leaf and the head; achene glabrous; heads 1 per plant; basal leaves (3.0-) 6.5-17.0 (-25.0) cm long, (0.4-) 0.6-1.0 (-1.5) cm wide, averaging ca. 10-15× as long as wide
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