Helianthus annuus |
Helianthus ciliaris |
|
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common sunflower, hairy leaf sunflower, sunflower |
blueweed, blueweed sunflower, Texas-blueweed, yerba parda |
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Habit | Annuals, 100–300 cm. | Perennials, 40–70 cm (rhizomatous or with creeping roots, often forming extensive colonies). |
Stems | erect, usually hispid. |
decumbent to ± erect, glabrous or glabrate (glaucous). |
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; mostly opposite; sessile; blades (often bluish green, 1- or 3-nerved) linear to lanceolate, 3–7.5 × 0.5–2.2 cm, bases ± cuneate, margins entire or serrate (usually ciliate and undulate), faces glabrous or glabrate to hispid. |
Peduncles | 2–20 cm. |
(1–)3–13 cm. |
Involucres | hemispheric or broader, 15–40(–200+) mm diam. |
hemispheric, 12–25 mm diam. |
Ray florets | (13–)17–30(–100+); laminae 25–50 mm. |
10–18; laminae 8–9 mm. |
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). |
35+; corollas 4–6 mm, lobes reddish; anthers brownish red, appendages brownish red (style branches yellow). |
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. |
16–19, ovate to lance-ovate, 3–8 × 2–3.5 mm, (margins ciliate) apices obtuse to acute, abaxial faces glabrate to ± strigose, not gland-dotted. |
Heads | 1–9. |
1–5. |
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. |
3–3.5 mm, glabrous; pappi of 2 aristate scales 1.2–1.5 mm. |
Paleae | 9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid). |
7–7.5 mm, subentire to 3-toothed (apices obtuse to acute, hairy, gland-dotted). |
2n | = 34. |
= 68, 102. |
Helianthus annuus |
Helianthus ciliaris |
|
Phenology | Flowering summer–fall. | Flowering summer–fall. |
Habitat | Open areas | Roadsides, ditches, cultivated fields, open drainage areas |
Elevation | 0–3000 m (0–9800 ft) | 10–2600 m (0–8500 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; IL; KS; NE; NM; NV; OK; TX; UT; Mexico (Chihuahua, Coahuila, Durango, San Luis Potosí, Sonora, Tamaulipas)
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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.) |
Helianthus ciliaris is considered a noxious weed in some states. It can propagate vegetatively from detached pieces of rhizome and spread aggressively, especially in cultivated fields. It has been noted to occur in Idaho and Washington, where control measures have been taken to eliminate it. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 21, p. 149. | FNA vol. 21, p. 169. |
Parent taxa | ||
Sibling 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) | de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 587. (1836) |
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