Helianthus annuus |
Helianthus floridanus |
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common sunflower |
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Habit | Plants annual, 10–30 dm. | |
Stems | erect, pustulose-hispid. |
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Leaves | mostly alternate; proximal pairs usually opposite, triangular to ovate or lanceolate, 3–30+ cm, bases truncate or rounded to attenuate; margins entire to serrate-dentate or denticulate; tips acute; surfaces spiculate or pustulose-hispid, sometimes setose on veins; petioles 1–7 cm. |
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Involucres | hemispheric, 15–40+ mm in diameter. |
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Ray florets | 12–30+; rays 25–50 mm. |
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Disc florets | 50+; corollas 5–8 mm; throats ± bulbous at base, gradually widened distally; lobes usually reddish; anthers dark; style appendages yellow to dark. |
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Phyllaries | 20–30(10) in 3+ series; ovate to lance-ovate, 10–25 × 5–8 mm; margins hispid-ciliate; tips acuminate; surfaces scabrous or hispid, rarely glabrous; outer gradually shorter. |
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Fruits | 3–10+ mm, glabrate, pappi of 2 lanceolate scales, 2–3.5 mm, with 0–4 additional smaller scales. |
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Heads | solitary to numerous. |
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Paleae | glabrous or hispid; inner tips 3-toothed. |
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2n | =34. |
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Helianthus annuus |
Helianthus floridanus |
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Distribution | ||
Discussion | Shrublands, pastures, banks of rivers and lakes, marshes, roadsides, disturbed areas. Flowering Jun–Sep. 0–1600 m. BR, BW, Col, CR, ECas, Lava, Owy, WV. CA, ID, NV, WA; throughout North America. Native. Helianthus annuus is one of the few North American natives to become a major cultivated crop. Sunflower seeds were exported from North America as early as the 16th century and are grown in much of the world both for their seeds and oil. |
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Source | Flora of Oregon, volume 2, page 281 Kenton Chambers |
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Sibling taxa | ||
Synonyms | Helianthus annuus ssp. annuus, Helianthus annuus ssp. lenticularis | |
Web links |
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