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FNA | Family List | FNA Vol. 21 | Asteraceae

385. Helenium Linnaeus, Sp. Pl. 2: 886. 1753; Gen. Pl. ed. 5, 377. 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.


1 Stems not winged   1 Helenium amarum
+ Stems ± winged (by decurrent leaf bases)   (2)
       
2 (1) Ray florets usually 8–34, neuter (if rays 0, perennials from e or se United States)   (3)
+ Ray florets usually 7–30, pistillate, fertile (if rays 0, plants either perennials from w United States or annuals)   (8)
       
3 (2) Heads 1(–3); disc corollas mostly yellow, sometimes yellow-brown distally   (4)
+ Heads 1–80+; disc corollas usually purple, sometimes red-brown or yellow-brown distally or throughout   (6)
       
4 (3) Pappus scales deeply lacerate; e Texas, sw Louisiana   2 Helenium drummondii
+ 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 (4) Leaves of basal rosettes usually pinnatifid; peduncles hairy; cypselae hairy   3 Helenium pinnatifidum
+ Leaves of basal rosettes usually entire; peduncles usually glabrous, some-times sparsely hairy; cypselae glabrous   4 Helenium vernale
       
6 (3) Heads (1–)5–50(–80); pappi of aristate scales   5 Helenium flexuosum
+ Heads 1–20; pappi of non-aristate scales   (7)
       
7 (6) Stems densely hairy proximally; leaves moderately to densely hairy; pappi 0.3–0.5 mm; nc Arkansas   6 Helenium campestre
+ Stems glabrous proximally; leaves glabrous or sparsely hairy; pappi 1–1.7 mm; se United States   7 Helenium brevifolium
       
8 (2) Perennials   (9)
+ Annuals   (13)
       
9 (8) Stems unbranched or sparingly branched distally   (10)
+ Stems strongly branched distally   (11)
       
10 (9) Peduncles usually densely hairy; pappi (2.5–)3–4.5 mm   11 Helenium bolanderi
+ Peduncles sparsely to moderately hairy; pappi 1.3–2.2(–2.7) mm   12 Helenium bigelovii
       
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)   10 Helenium puberulum (in part)
+ Rays 8–21, corollas 10–23 mm; disc corollas yellow to yellow-brown distally, lobes 5   (12)
       
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   8 Helenium autumnale
+ Leaves: basal blades oblanceolate (usually present at flowering), mid blades usually entire, sometimes dentate; swampy meadows, Missouri, Virginia   9 Helenium virginicum
       
13 (8) Pappi of aristate scales   (14)
+ Pappi of non-aristate scales   (16)
       
14 (13) Disc corolla lobes 4(–5); California   10 Helenium puberulum (in part)
+ Disc corolla lobes 5; Arizona, Texas   (15)
       
15 (14) Stems weakly winged (leaf bases scarcely decurrent from node to node); cypselae 2–2.9 mm; n Arizona   13 Helenium arizonicum
+ Stems narrowly winged (leaf bases decurrent from node to node); cypselae 1–1.2 mm; s Texas   14 Helenium linifolium
       
16 (13) Involucres globoid and distal leaves entire   15 Helenium elegans
+ Involucres usually ovoid to obconic (if globoid, distal leaves serrate to undulate-serrate)   (17)
       
17 (16) Distal leaves serrate to undulate-serrate; disc corolla lobes (4–)5   16 Helenium microcephalum
+ Distal leaves entire; disc corolla lobes 4   (18)
       
18 (17) Rays 10–15   17 Helenium quadridentatum
+ Rays 0   18 Helenium thurberi

  • List of lower taxa


     

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