Helianthus annuus |
Helianthus neglectus |
|
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common sunflower, hairy leaf sunflower, sunflower |
neglected sunflower |
|
Habit | Annuals, 100–300 cm. | Annuals, 80–200 cm. |
Stems | erect, usually hispid. |
erect (leafy), ± hispid to glabrate. |
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; alternate; petioles 7–12 cm; blades deltate-ovate, 7–14 × 7.5–12.3 cm, bases usually ± cordate, sometimes truncate, margins subentire to serrulate, abaxial faces strigose, not gland-dotted. |
Peduncles | 2–20 cm. |
10–40 cm. |
Involucres | hemispheric or broader, 15–40(–200+) mm diam. |
± hemispheric, (23–28 ×) 10–14 mm. |
Ray florets | (13–)17–30(–100+); laminae 25–50 mm. |
21–31; laminae 29–39 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). |
150+; corollas 6–6.5 mm, lobes reddish; anthers dark, appendages purplish (style branches reddish). |
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. |
25–35, lanceolate, 14–25 × 2.3–4 mm (surpassing discs), apices long-attenuate, abaxial faces strigillose to hispid. |
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. |
4–5 mm, strigillose to glabrate; pappi of 2 aristate scales 2.8–3.2 mm. |
Paleae | 9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid). |
9–10 mm, 3-toothed (middle teeth ± ciliate or bearded, hairs whitish, 0.3–0.6 mm). |
2n | = 34. |
= 34. |
Helianthus annuus |
Helianthus neglectus |
|
Phenology | Flowering summer–fall. | Flowering summer–fall. |
Habitat | Open areas | Sandy soils, sand dunes |
Elevation | 0–3000 m [0–9800 ft] | 800–1100 m [2600–3600 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
|
NM; TX |
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.) |
Of conservation concern. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 21, p. 149. | FNA vol. 21, p. 153. |
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) | Heiser: Rhodora 60: 275, fig. 2. (1958) |
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