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Published In: Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts 88: 189. 1819. (Mar 1819) (J. Phys. Chim. Hist. Nat. Arts) Name publication detailView in Biodiversity Heritage Library
 

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7. Tribe Heliantheae Cass.

Plants annual, biennial, or perennial herbs (sometimes woody elsewhere), sometimes from a woody rootstock, sometimes aromatic, occasionally monoecious, the sap not milky. Stems not spiny or prickly. Leaves alternate and/or opposite (whorled elsewhere), rarely only in a basal rosette, sessile to long-petiolate, not spiny or prickly. Leaf blades entire to lobed or pinnately compound, the venation pinnate or less commonly with 3 or more main veins. Inflorescences terminal panicles, spikes, or racemes, sometimes reduced to clusters of heads, or the heads solitary at the branch tips. Heads discoid or radiate. Involucre of 1 or 2 to more commonly several series of bracts, in a few genera these spiny or tuberculate. Receptacle flat to hemispherical or conical, naked or with chaffy bracts or hairs subtending all or some of the florets. Ray florets (when present) pistillate or sterile, sometimes inconspicuous, the corolla showy or sometimes very short or rarely absent, when present white, pink, purple, blue, yellow, or orange. Disc florets all perfect or functionally staminate, the corolla absent or highly reduced in a few monoecious genera, when present yellow, purple, purplish brown, the 4 or more commonly 5 lobes spreading to ascending. Pappus variously of numerous capillary bristles or 1 to several awns or scales, occasionally reduced to a minute crown or absent, when present persistent or not persisting at fruiting. Stamens with the filaments not fused together and the anthers fused into a tube or in a few genera with the filaments more or less fused into a tube and the anthers more or less free, each anther tip with a short to long appendage, each anther base truncate or less commonly with a pair of short lobes. Style branches somewhat flattened (the style undivided at maturity in functionally staminate flowers), each with a stigmatic line along each inner margin or more commonly with a stigmatic band along each inner surface, the sterile tip usually relatively long and tapered, less commonly short and truncate, usually with dense, minute hairs, at least on the outer surface. Fruits sometimes dimorphic (the outer series then thicker-walled and with different surface ornamentation), in a few genera enclosed in the persistent hardened involucre (forming a bur), sometimes somewhat flattened or angled to ribbed, variously shaped in profile, not beaked. About 300 genera, about 3,300 species, worldwide.

The Heliantheae are one of the largest and morphologically most diverse tribes in the family, which makes description of the tribe a challenge. The circumscription adopted here parallels that in the upcoming Asteraceae volumes of the Flora of North America series and differs from that adopted by Steyermark (1963) most notably in the inclusion of the genera that he separated as the tribe Helenieae Benth. Other recently proposed classifications, based mostly on molecular data, have varied widely, from those advocating the inclusion of the genera of Eupatorieae into a very broadly defined Heliantheae (Jansen and Kim, 1996; Bayer and Starr, 1998) to those who have suggested dissection of the Helenieae into six or more tribes in order to preserve the more traditional taxonomic circumscriptions of Heliantheae and Eupatorieae while providing formal recognition to each of the groups identified as monophyletic from the molecular data (Baldwin et al., 2002; Panero and Funk, 2002). Ultimately further research will be necessary to stabilize the limits of the Heliantheae and its sister tribes, and the present classification undoubtedly will have to be changed in the future to better reflect evolutionary relationships in the family.

A number of genera of Heliantheae contain members that are commonly cultivated as garden ornamentals and/or cut flowers, including Bidens, Coreopsis, Cosmos, Echinacea, Gaillardia, Helenium, Heliopsis, Rudbeckia, Tagetes, and Zinnia L. Helianthus is the most important crop genus, including H. annuus, the common sunflower, which is grown for its oil and seeds, as well as H. tuberosus, Jerusalem artichoke, which produces an edible tuberous root. Guizotia is the source of Niger thistle, which is a popular source of bird seed. On the negative side, a few genera contain species that are aggressive weeds of agricultural lands and producers of allergenic wind-borne pollen, including Ambrosia, Iva, and Xanthium.

 

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1 1. Heads discoid, none of the florets producing a ligulate corolla (note that some radiate genera with minute rays are keyed under both leads to minimize confusion)

2 2. Staminate and pistillate florets in different heads (none of the heads with perfect florets both staminate and pistillate florets), the staminate heads in terminal spikes or spikelike racemes, the pistillate heads appearing axillary below the staminate spikes; pistillate florets tightly enclosed by the involucral bracts, these persistent and with straight or hooked to curled spines or blunt tubercles on the outer surface

3 3. Staminate heads with the involucral bracts fused; pistillate heads with the involucral bracts having straight spines or blunt tubercles on the outer surface ... 64. AMBROSIA

Ambrosia
4 3. Staminate heads with the involucral bracts free; pistillate heads with the involucral bracts having sharp spines on the outer surface that are hooked or curled at the tip ... 95. XANTHIUM

Xanthium
5 2. Heads either with all of the florets perfect or with the marginal florets pistillate and the central florets perfect or functionally staminate; inflorescences various, but the heads all more or less similar; involucral bracts not enclosing the florets, the outer surface not spiny or tuberculate

6 4. Involucral bracts with prominent yellow to yellowish brown glandular dots or lines embedded in the outer surface; plants strongly aromatic when bruised or crushed ... 70. DYSSODIA

Dyssodia
7 4. Involucral bracts without glandular dots or lines embedded in the surface, either nonglandular or with inconspicuous, minute, sessile to stalked glands; plants not or only slightly aromatic when bruised or crushed

8 5. Receptacle naked, none of the florets subtended by chaffy bracts (note that minute, irregular ridges may surround the attachment points of the florets)

9 6. Leaves opposite; florets with the corolla yellow; involucral bracts apparently 3 per head, but with 2 additional minute bracts at the base of the head ... 74. FLAVERIA

Flaveria
10 6. Leaves alternate; florets with the corolla white to pale cream-colored or pink to purplish pink; involucral bracts more than 5 per head

11 7. Florets with the corolla white to pale cream-colored; inflorescence branches finely hairy, not glandular ... 81. HYMENOPAPPUS

Hymenopappus
12 7. Florets with the corolla pink to purplish pink; inflorescence branches with conspicuous, black, tack-shaped glands, otherwise glabrous ... 85. PALAFOXIA

Palafoxia
13 5. Receptacle chaffy, all or at least the outer florets subtended by chaffy bracts (the bracts appearing as slender, flattened bristles in Eclipta)

14 8. Pappus absent or a minute rim or crown

15 9. None of the florets perfect, the outer ones pistillate (lacking stamens), the inner ones functionally staminate with a small, stalklike ovary and an undivided style; stamens with the filaments fused into a tube, the anthers more or less free

16 10. Heads not subtended by bracts (small, leaflike bracts present only at the inflorescence branch points); involucral bracts free to the base; pistillate florets lacking a corolla ... 69. CYCLACHAENA

Cyclachaena
17 10. Each head subtended by a conspicuous bract; involucral bracts fused toward the base; pistillate florets with a tubular corolla 1.0–1.5 mm long ... 82. IVA

Iva
18 9. Florets mostly perfect, some of the outer ones only pistillate; stamens with the filaments free and the anthers fused into a tube

19 11. Leaf blades not lobed, finely toothed, narrowly lanceolate to elliptic in outline ... 72. ECLIPTA

Eclipta
20 11. Leaf blades pinnately lobed and irregularly toothed, broadly oblong to ovate in outline ... 87. POLYMNIA

Polymnia
21 8. Pappus present, of awns, scales, or bristles

22 12. Florets with the corolla yellow

23 13. Involucral bracts all free to the base ... 66. BIDENS

Bidens
24 13. Inner series of involucral bracts fused 1/4–2/3 of the way to the tip ... 93. THELESPERMA

Thelesperma
25 12. Florets with the corolla white to off-white or pale pink

26 14. Florets all perfect; leaves mostly basal ... 83. MARSHALLIA

Marshallia
27 14. None of the florets perfect, most of the florets staminate, a few of the outer ones pistillate; leaves basal and also well distributed along the stem ... 86. PARTHENIUM

Parthenium
28 1. Heads radiate, the rays well developed but sometimes with relatively short corollas

29 15. Receptacle naked, none of the florets subtended by chaffy bracts (note that minute, irregular ridges or hairs may surround the attachment points of the florets), or with slender bristles fused irregularly at the base

30 16. Involucral bracts with prominent yellow to yellowish brown glandular dots or lines embedded in the outer surface; plants strongly aromatic when bruised or crushed

31 17. Ray florets inconspicuous, the corolla 2–4 mm long; involucral bracts fused only at the base ... 70. DYSSODIA

Dyssodia
32 17. Ray florets showy, the corolla 10–30 mm long; involucral bracts fused to well above the midpoint ... 92. TAGETES

Tagetes
33 16. Involucral bracts without glandular dots or lines embedded in the surface, either nonglandular or with inconspicuous, minute, sessile to stalked glands; plants not or only slightly aromatic when bruised or crushed

34 18. Ray floret 1 per head, inconspicuous, the corolla 1.5–2.5 mm long; disc florets 3 or 4; involucral bracts in an inner series of 3 and an outer series of 2 much shorter bracts ... 74. FLAVERIA

Flaveria
35 18. Ray florets 5–21 per head, usually showy, the corolla 5–30 mm long; disc florets numerous; involucral bracts usually 14–20 in 2 or 3 series

36 19. Receptacle with numerous slender bristles fused irregularly at the base or these reduced to a network of low, irregular teeth; ray florets with the corolla red, brownish red, or reddish purple, at least toward the base (entirely yellow in G. aestivalis); disc florets with the corolla lobes woolly-hairy, not glandular; style branches with a relatively long, tapered, sterile tip ... 75. GAILLARDIA

Gaillardia
37 19. Receptacle naked, without bristles; ray florets yellow; disc florets with the corollas glandular; style branches with a relatively short, slightly expanded, more or less truncate, sterile tip ... 78. HELENIUM

Helenium
38 15. Receptacle chaffy, all or at least the outer florets subtended by chaffy bracts

39 20. Leaves all or mostly alternate (rarely appearing opposite or nearly so at a few nodes), occasionally all or mostly basal

40 21. None of the florets perfect, the disc florets staminate (with a small ovary and undivided style), the ray florets pistillate (lacking stamens)

41 22. Ray florets usually 5, the corolla 1–3 mm long, white or off-white ... 86. PARTHENIUM

Parthenium
42 22. Ray florets 7–35, the corolla 10–50 mm long, yellow

43 23. Ray florets (8–)13–35 in 2 or 3 overlapping marginal series, the corolla 15–50 mm long; involucre 15–40 mm long ... 90. SILPHIUM

Silphium
44 23. Ray florets (5–)8(–13) in 1 marginal series, the corolla 9–17 mm long; involucre 6–10 mm long

45 24. Leaf blades coarsely toothed or scalloped but not lobed; involucral bracts mostly broadly obovate to broadly rhombic, usually uniformly green, with a bluntly to sharply pointed tip; disc corollas brownish red to dark reddish purple ... 65. BERLANDIERA

Berlandiera
46 24. Leaf blades pinnately deeply lobed, the slender lobes often toothed or lobed; involucral bracts with a linear to narrowly oblong-lanceolate, green tip above a broader, thickened, yellowish base; disc corollas yellow ... 73. ENGELMANNIA

Engelmannia
47 21. Disc florets all perfect, the ray florets pistillate (lacking stamens or sterile) (producing neither stamens nor a style exserted from the corolla tube)

48 25. Leaf blades all or mostly deeply lobed ... 88. RATIBIDA

Ratibida
49 25. Leaf blades with the margins entire or variously scalloped or toothed, but not lobed

50 26. Receptacle noticeably conical or columnar

51 27. Chaffy bracts noticeably longer than the disc florets (including the corolla), tapered to a hard, spinelike tip; disc florets with the corolla slightly bulbous-thickened at the base ... 71. ECHINACEA

Echinacea
52 27. Chaffy bracts shorter than to slightly longer than the disc florets (including the corolla), truncate or rounded to angled or tapered to a sharply pointed tip, this unawned or with a soft, bristlelike awn; disc florets with the corolla not thickened at the base ... 89. RUDBECKIA

Rudbeckia
53 26. Receptacle flat or convex, but not noticeably elongate

54 28. Disc florets with the corollas dark reddish purple to purplish brown; ray florets with the corollas yellow ... 79. HELIANTHUS

Helianthus
55 28. Disc and ray florets with the corollas all yellow (sometimes greenish yellow toward the base of the disc corollas) or all white (in Verbesina virginica)

56 29. Leaf blades linear to narrowly lanceolate, the margins curled under, entire ... 79. HELIANTHUS

Helianthus
57 29. Leaf blades lanceolate to elliptic-lanceolate, ovate, or triangular, the margins relatively flat, toothed ... 94. VERBESINA

Verbesina
58 20. Leaves all or mostly opposite (sometimes alternate at the uppermost few nodes)

59 30. None of the florets perfect, the disc florets staminate (with a small ovary and undivided style), the ray florets pistillate (lacking stamens)

60 31. Ray florets with the corolla 2–10 mm long, white or pale cream-colored; involucre 3–8 mm long

61 32. Outer series of involucral bracts fused in the basal 1/6–1/3; inner involucral bracts folded around the ovary or fruit of a ray floret ... 84. MELAMPODIUM

Melampodium
62 32. Outer series of involucral bracts free to the base; inner involucral bracts relatively flat and not folded around the ray florets ... 87. POLYMNIA

Polymnia
63 31. Ray florets with the corolla 12–50 mm long, yellow; involucre 10–40 mm long

64 33. Leaf blades with the margins entire or toothed but not lobed; ray florets (8–)13–35 in 2 or 3 overlapping marginal series ... 90. SILPHIUM

Silphium
65 33. Leaf blades with 3 or less commonly 5 broad, irregular, triangular lobes, the margins also irregularly toothed; ray florets 7–13 in 1 marginal series ... 91. SMALLANTHUS

Smallanthus
66 30. Disc florets all perfect, the ray florets pistillate or sterile (producing neither stamens nor a style exserted from the corolla tube)

67 34. Ray florets with the corolla white or pink

68 35. Leaf blades deeply lobed or compound; ray florets with the corolla 5–40 mm long

69 36. Leaf blades mostly 1 time pinnately compound (the uppermost leaves sometimes only deeply lobed), the leaflets oblong-lanceolate to ovate, toothed; fruits narrowed or somewhat tapered at the tip but not beaked ... 66. BIDENS

Bidens
70 36. Leaf blades 1 or 2 times pinnately dissected, the ultimate segments linear to threadlike, mostly entire; fruits tapered to a noticeable beak ... 68. COSMOS

Cosmos
71 35. Leaf blades finely toothed but not lobed; ray florets with the corolla 1–3 mm long

72 37. Pappus absent or a minute rim or crown; involucral bracts 10–12 ... 72. ECLIPTA

73 37. Pappus of 12–20 fringed scales, sometimes highly reduced or absent in the ray florets; involucral bracts 6–9 ... 76. GALINSOGA

Galinsoga
74 34. Ray florets with the corolla yellow to orange, occasionally somewhat reddish-tinged toward the base

75 38. Disc florets with the corolla densely pubescent with tangled, more or less spreading hairs toward the base ... 77. GUIZOTIA

Guizotia
76 38. Disc florets with the corolla glabrous or rarely sparsely to densely pubescent with more or less appressed, straight hairs or glandular

77 39. Inner series of involucral bracts fused 1/4–2/3 of the way to the tip ... 93. THELESPERMA

Thelesperma
78 39. Involucral bracts all free or fused at the very base

79 40. Ray florets pistillate (with an exserted, forked style and an ovary similar in size to those of the disc florets at flowering, developing into a fruit)

80 41. Receptacle flat or broadly convex to shallowly conical; pappus of 2 slender to stout, stiff awns; fruits strongly flattened, the margins narrowly to broadly winged ... 94. VERBESINA

Verbesina
81 41. Receptacle noticeably conical or somewhat columnar; pappus absent or rarely of 1 or 2 minute, slender awns; fruits 3- or 4-angled or, if flattened, then the margins usually hairy but not winged

82 42. Stems spreading with ascending tips and branches, often rooting at the lower nodes; involucre 4–6 mm long; ray corollas not persistent at fruiting, the corolla 3–9 mm long; fruits flattened or those developing from the ray florets often somewhat 3-angled, the margins sparsely hairy ... 63. ACMELLA

Acmella
83 42. Stems erect or ascending, not rooting at the nodes (note that short rhizomes may be present); involucre 6–16 mm long; ray corollas becoming papery and persistent at fruiting, the corolla 15–40 mm long; fruits of the disc florets 4-angled, glabrous ... 80. HELIOPSIS

Heliopsis
84 40. Ray florets sterile (lacking a style at flowering and with an ovary that is shorter and thinner than those of the disc florets, not developing into a fruit)

85 43. Leaf blades deeply lobed or compound

86 44. Leaflets or lobes with the margins toothed ... 66. BIDENS

Bidens
87 44. Leaflets or lobes with the margins entire

88 45. Plants submerged aquatics with only the stem tips emergent ... 66. BIDENS

Bidens
89 45. Plants terrestrial, at most growing in moist soil along stream banks but often in drier habitats

90 46. Ray florets with the corolla yellow to occasionally orangish yellow; pappus absent or of a few short bristles but more commonly of 2 short, slender scales or awns (these smooth or with sparse, upward-angled barbs); fruits 2–7 mm long, flattened, more or less truncate at the tip, not beaked ... 67. COREOPSIS

Coreopsis
91 46. Ray florets with the corolla yellowish orange to reddish orange; pappus of 2–4 short awns (these with downward-angled barbs) or rarely absent; fruits 7–30 mm long (including the beak), not flattened, 4-angled, tapered to a noticeable beak at the tip ... 68. COSMOS

Cosmos
92 43. Leaf blades simple, unlobed, the margins entire to variously toothed or scalloped

93 47. Involucral bracts of 2 distinct types, the outer series green and more or less herbaceous, ascending or spreading, the inner series membranous to scalelike, reddish-, brownish-, or yellowish-tinged and with numerous fine longitudinal nerves or lines, erect or strongly ascending

94 48. Leaf blades with the margins toothed; outer series of involucral bracts as long as or mostly longer than the inner series ... 66. BIDENS

Bidens
95 48. Leaf blades with the margins entire; outer series of involucral bracts shorter than the inner series ... 67. COREOPSIS

Coreopsis
96 47. Involucral bracts in 1 to several series of similar or different lengths, but all similar in color and texture, green and herbaceous from a sometimes yellowish base, without numerous longitudinal nerves or lines, erect to spreading

97 49. Pappus of 2 awns with broad, flattened bases (or less commonly scales) that usually are shed prior to fruit maturity; fruits 4-angled or somewhat flattened with blunt to rounded margins, not winged ... 79. HELIANTHUS

Helianthus
98 49. Pappus of 2 awns that are persistent at fruiting; fruits strongly flattened, the margins sharply angled or more commonly winged ... 94. VERBESINA Verbesina
 
 
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