Helianthus annuus |
Helianthus nuttallii |
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common sunflower, hairy leaf sunflower, sunflower |
hélianthe de Nuttall, Nuttall's sunflower |
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Habit | Annuals, 100–300 cm. | Perennials, 100–400 cm (rhizomatous). | ||||||||
Stems | erect, usually hispid. |
(usually yellow-brown or greenish, sometimes glaucous) erect, glabrous, hispid, ± hirsute, or scabrous. |
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Leaves | mostly cauline; mostly alternate; petioles 2–20 cm; blades lance-ovate to ovate, 10–40 × 5–40 cm, bases cuneate to subcordate or cordate, margins serrate, abaxial faces usually ± hispid, sometimes gland-dotted. |
cauline; all or mostly opposite to mostly alternate; petioles 0.5–1.5 cm; blades light to dark green, 3-nerved (distal to bases) ± lanceolate to ± ovate, 4–20 × 0.8–4 cm, bases cuneate, margins entire or ± serrate (flat), abaxial faces hispid to hispidulous or tomentulose to villous-tomentose, gland-dotted. |
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Peduncles | 2–20 cm. |
1–18 cm. |
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Involucres | hemispheric or broader, 15–40(–200+) mm diam. |
hemispheric, 10–20 mm diam. |
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Ray florets | (13–)17–30(–100+); laminae 25–50 mm. |
10–21; laminae 20–25 mm (abaxial faces not gland-dotted). |
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Disc florets | 150+(–1000+); corollas 5–8 mm (throats ± bulbous at bases), lobes usually reddish, sometimes yellow; anthers brownish to black, appendages yellow or dark (style branches yellow). |
60+; corollas 5–7 mm, lobes yellow; anthers dark brown to black, appendages yellow. |
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Phyllaries | 20–30(–100+), ovate to lance-ovate, 13–25 × (3–)5–8 mm, (margins usually ciliate) apices abruptly narrowed, long-acuminate, abaxial faces usually hirsute to hispid, rarely glabrate or glabrous, usually gland-dotted. |
30–38 (loose, spreading), lanceolate to lance-ovate, 8–16 × 1.5–3 mm, (margins ciliate) apices acute to acuminate, abaxial faces usually ± strigose, rarely glabrate, not gland-dotted. |
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Heads | 1–9. |
1–6. |
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Cypselae | (3–)4–5(–15) mm, glabrate; pappi of 2 lanceolate scales 2–3.5 mm plus 0–4 obtuse scales 0.5–1 mm. |
3–5 mm, glabrate; pappi of 2 aristate scales 2.2–4.5 mm plus 0–2 lanceolate scales 0.5–1 mm. |
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Paleae | 9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid). |
8–12 mm, 3-toothed. |
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2n | = 34. |
= 34 (subspecies unknown). |
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Helianthus annuus |
Helianthus nuttallii |
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Phenology | Flowering summer–fall. | |||||||||
Habitat | Open areas | |||||||||
Elevation | 0–3000 m [0–9800 ft] | |||||||||
Distribution |
AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; NT; ON; PE; QC; SK; SPM; Mexico; intoduced nearly worldwide
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AZ; CA; CO; IA; ID; KS; MN; MO; MT; ND; NE; NM; NV; OK; OR; SD; UT; WA; WY; AB; BC; MB; ON; QC; SK
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Discussion | Helianthus annuus is widely distributed, including weedy, cultivated, and escaped plants. It is the only native North American species to become a major agronomic crop. Despite its considerable variability, attempts have failed to produce a widely adopted infraspecific system of classification. Forms with red-colored ray laminae, known from cultivation and occasionally seen escaped, trace their ancestry to a single original mutant plant. It hybridizes with many of the other annual species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Subspecies 3 (3 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 21, p. 149. | FNA vol. 21, p. 166. | ||||||||
Parent taxa | ||||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | H. annuus subsp. jaegeri, H. annuus subsp. lenticularis, H. annuus var. lenticularis, H. annuus var. macrocarpus, H. annuus subsp. texanus, H. aridus, H. jaegeri, H. lenticularis, H. macrocarpus | |||||||||
Name authority | Linnaeus: Sp. Pl. 2: 904. (1753) | Torrey & A. Gray: Fl. N. Amer. 2: 324. (1842) | ||||||||
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