Helianthus annuus |
Helianthus deserticola |
|
---|---|---|
common sunflower, hairy leaf sunflower, sunflower |
desert sunflower |
|
Habit | Annuals, 100–300 cm. | Annuals, 10–40 cm. |
Stems | erect, usually hispid. |
(green or red) erect, densely hirsute and gland-dotted. |
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 1–6 cm; blades lanceolate to lance-ovate, 2.5–5 × 1–2 cm, bases cuneate, margins entire, abaxial faces hispid-hirsute, densely gland-dotted. |
Peduncles | 2–20 cm. |
1–3(–8) cm. |
Involucres | hemispheric or broader, 15–40(–200+) mm diam. |
hemispheric, 13–25 mm diam. |
Ray florets | (13–)17–30(–100+); laminae 25–50 mm. |
7–13; laminae 10–30 mm (abaxial faces gland-dotted). |
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). |
25+; corollas 5.5–6 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. |
13–21, lanceolate to lance-ovate, 7–19 × 1.5–2 mm (equaling or slightly surpassing discs), (margins ciliate) apices acuminate, abaxial faces hispid (hairs erect, often 1+ mm) 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. |
4–5 mm, pilose; pappi usually of 2 linear scales 1.6–2.5 mm plus 4–6 linear or ovate, erose scales 0.5–1 mm. |
Paleae | 9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid). |
8–9 mm, ± 3-toothed (middle teeth equaling or slightly surpassing discs, apices yellowish brown, usually hispid). |
2n | = 34. |
= 34. |
Helianthus annuus |
Helianthus deserticola |
|
Phenology | Flowering summer–fall. | Flowering spring–fall. |
Habitat | Open areas | Dry, open areas |
Elevation | 0–3000 m [0–9800 ft] | 400–1500 m [1300–4900 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
|
AZ; NV; UT |
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 deserticola is relatively uncommon; it is not federally listed. Abundant subsessile glands (“resin dots”) on stems, leaves, phyllaries, and abaxial faces of ray laminae help to distinguish H. deserticola from H. anomalus, with which it is sometimes lumped. L. H. Rieseberg (1991) demonstrated that it is of hybrid origin; parental species are H. annuus and H. petiolaris. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 21, p. 149. | FNA vol. 21, p. 154. |
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: Proc. Indiana Acad. Sci. 70: 209, fig. 1. (1960) |
Web links |
|