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385. Helenium Linnaeus, Sp. Pl. 2: 886. 1753; Gen. Pl. ed. 5, 377 (as Helenia). 1754.
Sneezeweed [For Helen of Troy]
Mark W. Bierner
Annuals or perennials, 10–160 cm. Stems 1(–10), erect, simple or branched distally (usually ± winged by decurrent leaf bases), glabrous or sparsely to densely hairy. Leaves usually mostly cauline; mostly alternate (proximal sometimes opposite); petiolate or sessile; blades mostly elliptic, lanceolate, linear, oblanceolate, oblong, ovate, or spatulate, often pinnately lobed or pinnatifid, ultimate margins entire or toothed, faces glabrous or sparsely to densely hairy, gland-dotted. Heads radiate or discoid, borne singly or (2–300+) in paniculiform to corymbiform arrays. Involucres ± globose, hemispheric, obconic, or ovoid, 4–34 mm diam. Phyllaries persistent, 9–34(–40+) in (1–)2[–3] series (distinct or proximally connate, usually reflexed in fruit, glabrous or sparsely to densely hairy, gland-dotted). Receptacles conic, ± globose, hemispheric, or ovoid, pitted (glabrous), epaleate (rarely bearing setiform enations). Ray florets 0 or 7–34, pistillate and fertile or neuter; corollas yellow, yellow with purple streaks, reddish brown to red proximally and yellow distally, or reddish brown to red or purple throughout. Disc florets 75–1000+, bisexual, fertile; corollas yellow, purple, or yellow to yellow-green proximally and yellow-brown, brown or reddish brown to purple distally, tubes shorter than throats, lobes 4 or 5, ± deltate (style-branch apices penicillate or truncate). Cypselae mostly obpyramidal, 4–5-angled, glabrous or sparsely to densely hairy; pappi persistent, of 5–12 entire or ± lacerate, sometimes aristate scales. x = 17.
Species ca. 32 (18 in the flora): North America, Mexico, West Indies (Cuba), Central America, South America.
Helenium polyphyllum Small is apparently a hybrid between H. autumnale and H. flexuosum.
SELECTED REFERENCES Bierner, M. W. 1972. Taxonomy of Helenium sect. Tetrodus and a conspectus of North American Helenium (Compositae). Brittonia 24: 331–355. Bierner, M. W. 1989. Taxonomy of Helenium sect. Amarum (Asteraceae). Sida 13: 453–459. Rock, H. F. L. 1957. A revision of the vernal species of Helenium (Compositae). Rhodora 59: 101–116, 128–158, 168–178, 203–216.
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| 1 |
Stems not winged |
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1 Helenium amarum |
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Stems ± winged (by decurrent leaf bases) |
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(2) |
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| 2 (1) |
Ray florets usually 8–34, neuter (if rays 0, perennials from e or se United States) |
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(3) |
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Ray florets usually 7–30, pistillate, fertile (if rays 0, plants either perennials from w United States or annuals) |
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(8) |
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| 3 (2) |
Heads 1(–3); disc corollas mostly yellow, sometimes yellow-brown distally |
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(4) |
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Heads 1–80+; disc corollas usually purple, sometimes red-brown or yellow-brown distally or throughout |
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(6) |
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| 4 (3) |
Pappus scales deeply lacerate; e Texas, sw Louisiana |
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2 Helenium drummondii |
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Pappus scales entire or slightly lacerate (never deeply lacerate); se Louisiana, s Mississippi, s Alabama, s Georgia, se South Carolina, s North Carolina, Florida |
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(5) |
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| 5 (4) |
Leaves of basal rosettes usually pinnatifid; peduncles hairy; cypselae hairy |
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3 Helenium pinnatifidum |
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Leaves of basal rosettes usually entire; peduncles usually glabrous, some-times sparsely hairy; cypselae glabrous |
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4 Helenium vernale |
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| 6 (3) |
Heads (1–)5–50(–80); pappi of aristate scales |
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5 Helenium flexuosum |
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Heads 1–20; pappi of non-aristate scales |
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(7) |
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| 7 (6) |
Stems densely hairy proximally; leaves moderately to densely hairy; pappi 0.3–0.5 mm; nc Arkansas |
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6 Helenium campestre |
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Stems glabrous proximally; leaves glabrous or sparsely hairy; pappi 1–1.7 mm; se United States |
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7 Helenium brevifolium |
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| 8 (2) |
Perennials |
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(9) |
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Annuals |
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(13) |
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| 9 (8) |
Stems unbranched or sparingly branched distally |
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(10) |
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Stems strongly branched distally |
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(11) |
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| 10 (9) |
Peduncles usually densely hairy; pappi (2.5–)3–4.5 mm |
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11 Helenium bolanderi |
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Peduncles sparsely to moderately hairy; pappi 1.3–2.2(–2.7) mm |
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12 Helenium bigelovii |
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| 11 (9) |
Rays usually 13–15, sometimes 0, corollas 3.8–10 mm; disc corollas yel-low to reddish brown or purple distally, lobes 4(–5) |
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10 Helenium puberulum (in part) |
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Rays 8–21, corollas 10–23 mm; disc corollas yellow to yellow-brown distally, lobes 5 |
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(12) |
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| 12 (11) |
Leaves: basal blades oblanceolate, obovate, or spatulate (withered by flowering), mid blades usually dentate, distal blades entire or dentate; United States and s Canada |
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8 Helenium autumnale |
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Leaves: basal blades oblanceolate (usually present at flowering), mid blades usually entire, sometimes dentate; swampy meadows, Missouri, Virginia |
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9 Helenium virginicum |
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| 13 (8) |
Pappi of aristate scales |
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(14) |
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Pappi of non-aristate scales |
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(16) |
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| 14 (13) |
Disc corolla lobes 4(–5); California |
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10 Helenium puberulum (in part) |
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Disc corolla lobes 5; Arizona, Texas |
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(15) |
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| 15 (14) |
Stems weakly winged (leaf bases scarcely decurrent from node to node); cypselae 2–2.9 mm; n Arizona |
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13 Helenium arizonicum |
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Stems narrowly winged (leaf bases decurrent from node to node); cypselae 1–1.2 mm; s Texas |
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14 Helenium linifolium |
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| 16 (13) |
Involucres globoid and distal leaves entire |
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15 Helenium elegans |
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Involucres usually ovoid to obconic (if globoid, distal leaves serrate to undulate-serrate) |
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(17) |
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| 17 (16) |
Distal leaves serrate to undulate-serrate; disc corolla lobes (4–)5 |
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16 Helenium microcephalum |
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Distal leaves entire; disc corolla lobes 4 |
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(18) |
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| 18 (17) |
Rays 10–15 |
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17 Helenium quadridentatum |
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Rays 0 |
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18 Helenium thurberi |
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List of lower taxa
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