Helianthus annuus |
Helianthus agrestis |
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common sunflower, hairy leaf sunflower, sunflower |
southeastern sunflower |
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Habit | Annuals, 100–300 cm. | Annuals, 100(–200+) cm. |
Stems | erect, usually hispid. |
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. |
mostly cauline; mostly opposite; petioles 0.5–1.2 cm; blades (often 3-nerved distal to bases) lanceolate, 6–11 × 0.7–1.9 cm, bases cuneate, margins ± serrate, faces scabrous, not gland-dotted. |
Peduncles | 2–20 cm. |
2–8 cm. |
Involucres | hemispheric or broader, 15–40(–200+) mm diam. |
hemispheric, 10–15 mm diam. |
Ray florets | (13–)17–30(–100+); laminae 25–50 mm. |
ca. 12; laminae 12–25 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). |
50+; corollas 3.5–4 mm, lobes reddish purple; 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. |
15–25, lanceolate, 8–9 × 1.5–2 mm, (margins ciliate) apices acuminate, abaxial faces glabrate. |
Heads | 1–9. |
1–15. |
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. |
2.5–3.2 mm, glabrous (± tuberculate); pappi of 2 aristate scales 1.5–2 mm. |
Paleae | 9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid). |
5–7, subentire to ± 3-toothed (apices purplish, glabrous). |
2n | = 34. |
= 34. |
Helianthus annuus |
Helianthus agrestis |
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Phenology | Flowering summer–fall. | Flowering late summer to fall. |
Habitat | Open areas | Mucky wet soils, marshes, pine flatwoods |
Elevation | 0–3000 m [0–9800 ft] | 0–50+ m [0–160+ 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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FL; GA |
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.) |
Distinctive among species of Helianthus with an annual habit in having a combination of reddish disc corolla lobes and yellow style branches, H. agrestis is also characterized by its glabrate stems and phyllaries and by relatively long hairs on the petioles and basal margins of the leaves. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 21, p. 149. | FNA vol. 21, p. 148. |
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) | Pollard: Proc. Biol. Soc. Wash. 13: 184. (1900) |
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