Helianthus annuus
Helianthus grosseserratus
common sunflower, hairy leaf sunflower, sunflower
hélianthe à grosses dents, saw-tooth sunflower
erect, usually hispid.
erect, glabrous proximally, distally glabrate, scabrellous, or strigillose (glaucous).
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; opposite (proximal) or alternate;
petioles (1–)2–5 cm;
blades (light to dark green, 3-nerved distal to bases) lanceolate to lance-ovate, 10–32 × (1.2–)4–9 cm, bases cuneate, margins usually coarsely to shallowly serrate, rarely subentire (flat), abaxial faces puberulent to tomentulose, gland-dotted.
2–20 cm.
0.3–10 cm.
hemispheric or broader, 15–40(–200+) mm diam.
(13–)17–30(–100+);
laminae 25–50 mm.
14–20;
laminae 23–40 mm.
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).
100+;
corollas 5–6 mm, lobes yellow;
anthers dark brown to black, appendages yellow.
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.
25–30 (loose, spreading), lance-linear, 10–14 × 1.5–2.5 mm (subequal), (margins ± ciliate) apices attenuate, abaxial faces glabrous or puberulent, not gland-dotted.
1–9.
3–15+.
(3–)4–5(–15) mm, glabrate;
pappi of 2 lanceolate scales 2–3.5 mm plus 0–4 obtuse scales 0.5–1 mm.
3–4 mm, glabrate;
pappi of 2 aristate scales 1.9–2.5 mm.
9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid).
7–8 mm, entire or 3-toothed (apices acuminate, ± hairy).
-lucres broadly hemispheric, 15–25 mm diam.
= 34.
= 34.
Helianthus annuus
Helianthus grosseserratus
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 grosseserratus is native to midwestern North America and has spread as a roadside weed into other areas, such as New England and the southeastern United States. It is introduced in Canada. Hybrids between H. maximiliani and H. grosseserratus are known as H. ×intermedius R. W. Long (R. W. Long 1954; Long 1966). Hybrids of H. grosseserratus with H. salicifolius have been described as H. kellermannii Britton (Long 1955), and those with H. mollis as H. brevifolius E. Watson (R. C. Jackson and A. T. Guard 1957b).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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