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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 entire; pappus scales 0.05-0.2 mm long
............ ....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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