Helianthus annuus |
Helianthus resinosus |
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common sunflower, hairy leaf sunflower, sunflower |
resindot sunflower |
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Habit | Annuals, 100–300 cm. | Perennials, 100–300 cm (rhizomatous). |
Stems | erect, usually hispid. |
(often reddish or purplish) erect, hirsute or villous. |
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. |
mostly cauline; mostly alternate; petioles 0.5–2 cm (broadly winged); blades lanceolate to ovate, 6.5–20 × 3.2–9 cm, bases gradually narrowed (onto petioles), margins entire or serrate, abaxial faces hirsute to tomentose, gland-dotted. |
Peduncles | 2–20 cm. |
1–3 cm. |
Involucres | hemispheric or broader, 15–40(–200+) mm diam. |
hemispheric, 15–27 mm diam. |
Ray florets | (13–)17–30(–100+); laminae 25–50 mm. |
10–20; laminae (often light yellow) 18–30 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). |
90+; corollas 8–8.5 mm, lobes yellow; anthers dark, appendages dark. |
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. |
20–30 (squarrose to reflexed, at least tips), lanceolate, 10–21 × 3–5 mm (notably surpassing discs), apices acute to attenuate, abaxial faces hispid to villous, densely gland-dotted (at least toward apices). |
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. |
5–7 mm, glabrate; pappi of 2 aristate scales 2.4–2.6 mm. |
Paleae | 9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid). |
9–11 mm, 3-toothed (gland-dotted). |
2n | = 34. |
= 102. |
Helianthus annuus |
Helianthus resinosus |
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Phenology | Flowering summer–fall. | Flowering late summer–fall. |
Habitat | Open areas | Roadsides, open areas |
Elevation | 0–3000 m [0–9800 ft] | 0–900+ m [0–3000+ 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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AL; FL; GA; MS; NC; SC
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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.) |
Consistent with its epithet, Helianthus resinosus has abundant subsessile glandular hairs (“resin dots”) on its leaves, phyllaries, paleae, and ray laminae. It intergrades and has been reported to hybridize with H. tuberosus. It is cultivated and usually sold under the long-misapplied name H. tomentosus Michaux. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 21, p. 149. | FNA vol. 21, p. 162. |
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) | Small: Fl. S.E. U.S., 1269, 1340. (1903) |
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