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 yellowbrown, 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.

Distribution

North America, Mexico, West Indies (Cuba), Central America, South America

Discussion

Species ca. 32 (18 in the flora).

Helenium polyphyllum Small is apparently a hybrid between H. autumnale and H. flexuosum.

Key

1 Stems not winged Helenium amarum
1 Stems ± winged (by decurrent leaf bases) > 2
2 Ray florets usually 8–34, neuter (if rays 0, perennials from e or se United States) > 3
2 Ray florets usually 7–30, pistillate, fertile (if rays 0, plants either perennials from w United States or annuals) > 8
3 Heads 1(–3); disc corollas mostly yellow, sometimes yellow-brown distally > 4
3 Heads 1–80+; disc corollas usually purple, sometimes red-brown or yellow-brown distally or throughout > 6
4 Pappus scales deeply lacerate; e Texas, sw Louisiana Helenium drummondii
4 Pappus scales entire or slightly lacerate (never deeply lacerate); se Louisiana, s Mississippi, s Alabama, s Georgia, se South Carolina, s North Carolina, Florida > 5
5 Leaves of basal rosettes usually pinnatifid; peduncles hairy; cypselae hairy Helenium pinnatifidum
5 Leaves of basal rosettes usually entire; peduncles usually glabrous, sometimes sparsely hairy; cypselae glabrous Helenium vernale
6 Heads (1–)5–50(–80); pappi of aristate scales Helenium flexuosum
6 Heads 1–20; pappi of non-aristate scales > 7
7 Stems densely hairy proximally; leaves moderately to densely hairy; pappi 0.3–0.5 mm; nc Arkansas Helenium campestre
7 Stems glabrous proximally; leaves glabrous or sparsely hairy; pappi 1–1.7 mm; se United States Helenium brevifolium
8 Perennials > 9
8 Annuals > 13
9 Stems unbranched or sparingly branched distally > 10
9 Stems strongly branched distally > 11
10 Peduncles usually densely hairy; pappi (2.5–)3–4.5 mm Helenium bolanderi
10 Peduncles sparsely to moderately hairy; pappi 1.3–2.2(–2.7) mm Helenium bigelovii
11 Rays usually 13–15, sometimes 0, corollas 3.8–10 mm; disc corollas yello to reddish brown or purple distally, lobes 4(–5) Helenium puberulum
11 Rays 8–21, corollas 10–23 mm; disc corollas yellow to yellow-brown distally, lobes 5 > 12
12 Leaves: basal blades oblanceolate, obovate, or spatulate (withered by flowering), mid blades usually dentate, distal blades entire or dentate; United States and s Canada Helenium autumnale
12 Leaves: basal blades oblanceolate (usually present at flowering), mid blades usually entire, sometimes dentate; swampy meadows, Missouri, Virginia Helenium virginicum
13 Pappi of aristate scales > 14
13 Pappi of non-aristate scales > 16
14 Disc corolla lobes 4(–5); California Helenium puberulum
14 Disc corolla lobes 5; Arizona, Texas > 15
15 Stems weakly winged (leaf bases scarcely decurrent from node to node); cypselae 2–2.9 mm; n Arizona Helenium arizonicum
15 Stems narrowly winged (leaf bases decurrent from node to node); cypselae 1–1.2 mm; s Texas Helenium linifolium
16 Involucres globoid and distal leaves entire Helenium elegans
16 Involucres usually ovoid to obconic (if globoid, distal leaves serrate to undulate-serrate) > 17
17 Distal leaves serrate to undulate-serrate; disc corolla lobes (4–)5 Helenium microcephalum
17 Distal leaves entire; disc corolla lobes 4 > 18
18 Rays 10–15 Helenium quadridentatum
18 Rays 0 Helenium thurberi
... more about "Helenium"
not tailed +, rounded +  and obtuse +
connate +  and distinct +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
paniculiform +  and corymbiform +
indeterminate +  and determinate +
Mark W. Bierner +
Linnaeus +
decurrent +
compound +  and simple +
pinnatifid;lobed;spatulate;ovate;spatulate;ovate;oblong;oblanceolate;linear;lanceolate;elliptic +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
barbellulate +  and barbellate +
Sneezeweed +
yellow +  and yellow-green proximally and yellowbrown punct brown or reddish-brown +
glabrous or +  and sparsely densely hairy +
4-5-angled +  and obpyramidal +
fertile +  and bisexual +
fertile +  and bisexual +
North America +, Mexico +, West Indies (Cuba) +, Central America +  and South America +
For Helen of Troy +
gland-dotted +
glabrous or +  and sparsely densely hairy +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
discoid +  and radiate +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
0.4 cm4 mm <br />0.004 m <br /> (3.4 cm34 mm <br />0.034 m <br />) +
ovoid;obconic;ovoid;obconic;hemispheric;globose +
sessile +  and petiolate +
deltate +
dentate to pinnatifid or palmatifid +  and entire +
connate +  and distinct +
ovate +, oblong +, oblanceolate +, linear +, lanceolate +  and elliptic +
unequal +  and subequal +
2-carpellate +
persistent +
9 +  and 34 +
Sp. Pl. +  and Gen. Pl. ed. +
1753 +  and 1754 +
neuter +  and pistillate +
bearing subulate enations +, hairy +  and bristly +
ovoid;hemispheric;ovoid;hemispheric;globose;conic +
bierner1972a +, bierner1989a +  and rock1957a +
5 +  and 12 +
aristate +, lacerate +  and entire +
exalbuminous +
branched +  and simple +
1 (?) +  and 10 (?) +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Compositae +
Helenium +
Asteraceae (tribe Heliantheae) subtribe Gaillardiinae +
urceolate +  and campanulate +
dilated +
toothed +  and entire +
perennial +  and annual +
10 cm100 mm <br />0.1 m <br /> (160 cm1,600 mm <br />1.6 m <br />) +
shrub +  and subshrub +