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Thurber's sneezeweed

sneezeweed

Habit Annuals, 40–100 cm. Annuals or perennials, 10–160 cm.
Stems

usually 1, branched distally, moderately winged, sparsely hairy proximally, moderately hairy distally.

1(–10), erect, simple or branched distally (usually ± winged by decurrent leaf bases), glabrous or sparsely to densely hairy.

Leaves

glabrous or sparsely hairy (basal leaves withered by flowering);

proximal blades lanceolate to lance-linear, usually irregularly laciniate;

mid and distal blades lance-linear, entire.

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.

Peduncles

3–10 cm, moderately hairy.

Involucres

ovoid to conic, 6–10 × 5–10 mm.

± globose, hemispheric, obconic, or ovoid, 4–34 mm diam.

Receptacles

conic, ± globose, hemispheric, or ovoid, pitted (glabrous), epaleate (rarely bearing setiform enations).

Ray florets

0.

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

225–500+;

corollas yellow-green proximally, brown to reddish brown distally, 1–1.3 mm, lobes 4.

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).

Phyllaries

(strongly connate proximally), moderately hairy.

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).

Heads

10–75(–120+) per plant, in paniculiform arrays.

radiate or discoid, borne singly or (2–300+) in paniculiform to corymbiform arrays.

Cypselae

0.9–1.2(–1.5) mm, moderately hairy;

pappi of 6(–7) entire, non-aristate scales 0.2–0.5 mm.

mostly obpyramidal, 4–5-angled, glabrous or sparsely to densely hairy;

pappi persistent, of 5–12 entire or ± lacerate, sometimes aristate scales.

x

= 17.

2n

= 26.

Helenium thurberi

Helenium

Phenology Flowering (Mar–)May–Jul(–Sep).
Habitat Ditches, around ponds, along streams, moist fields
Elevation 30–1600 m (100–5200 ft)
Distribution
from FNA
AZ; Mexico
[WildflowerSearch map]
[BONAP county map]
from USDA
North America; Mexico; Central America; South America; West Indies (Cuba)
[BONAP county map]
Discussion

Species ca. 32 (18 in the flora).

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

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Stems not winged
H. 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
H. 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
H. pinnatifidum
5. Leaves of basal rosettes usually entire; peduncles usually glabrous, sometimes sparsely hairy; cypselae glabrous
H. vernale
6. Heads (1–)5–50(–80); pappi of aristate scales
H. 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
H. campestre
7. Stems glabrous proximally; leaves glabrous or sparsely hairy; pappi 1–1.7 mm; se United States
H. 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
H. bolanderi
10. Peduncles sparsely to moderately hairy; pappi 1.3–2.2(–2.7) mm
H. 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)
H. 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
H. autumnale
12. Leaves: basal blades oblanceolate (usually present at flowering), mid blades usually entire, sometimes dentate; swampy meadows, Missouri, Virginia
H. virginicum
13. Pappi of aristate scales
→ 14
13. Pappi of non-aristate scales
→ 16
14. Disc corolla lobes 4(–5); California
H. 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
H. arizonicum
15. Stems narrowly winged (leaf bases decurrent from node to node); cypselae 1–1.2 mm; s Texas
H. linifolium
16. Involucres globoid and distal leaves entire
H. 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
H. microcephalum
17. Distal leaves entire; disc corolla lobes 4
→ 18
18. Rays 10–15
H. quadridentatum
18. Rays 0
H. thurberi
Source FNA vol. 21, p. 434. FNA vol. 21, p. 426. Author: Mark W. Bierner.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Gaillardiinae > Helenium Asteraceae > tribe Heliantheae > subtribe Gaillardiinae
Sibling taxa
H. amarum, H. arizonicum, H. autumnale, H. bigelovii, H. bolanderi, H. brevifolium, H. campestre, H. drummondii, H. elegans, H. flexuosum, H. linifolium, H. microcephalum, H. pinnatifidum, H. puberulum, H. quadridentatum, H. vernale, H. virginicum
Subordinate taxa
H. amarum, H. arizonicum, H. autumnale, H. bigelovii, H. bolanderi, H. brevifolium, H. campestre, H. drummondii, H. elegans, H. flexuosum, H. linifolium, H. microcephalum, H. pinnatifidum, H. puberulum, H. quadridentatum, H. thurberi, H. vernale, H. virginicum
Name authority A. Gray: Proc. Amer. Acad. Arts 19: 32. (1883) Linnaeus: Sp. Pl. 2: 886. (1753): Gen. Pl. ed. 5, 377. (1754) — (as Helenia)
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