Helianthus annuus
Helianthus divaricatus
common sunflower, hairy leaf sunflower, sunflower
woodland sunflower
erect, usually hispid.
erect, usually glabrous, rarely ± hairy (often 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;
sessile;
blades (light to dark green, sometimes whitish abaxially, 3-nerved at bases) lanceolate to lance-ovate, 6–15 × 1–5 cm, bases rounded to cordate, margins subentire to serrate, abaxial faces sparsely hispid to hispidulous, gland-dotted.
2–20 cm.
0.5–9 cm.
hemispheric or broader, 15–40(–200+) mm diam.
hemispheric, 10–15 mm diam.
(13–)17–30(–100+);
laminae 25–50 mm.
8–12;
laminae 15–30 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).
40+;
corollas 4.2–5.5 mm, lobes yellow;
anthers usually 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.
18–25, lanceolate, lance-linear, or lance-ovate, 6–12 × 2–2.5 mm, (margins ciliate) apices acuminate to attenuate, abaxial faces hispidulous to glabrate, not gland-dotted.
1–9.
1–10.
(3–)4–5(–15) mm, glabrate;
pappi of 2 lanceolate scales 2–3.5 mm plus 0–4 obtuse scales 0.5–1 mm.
3–3.6 mm, glabrate;
pappi of 2 aristate scales 2.2–2.5 mm.
9–11 mm, 3-toothed (middle teeth long-acuminate, glabrous or hispid).
5–8 mm, 3-toothed (apices ciliate).
= 34.
= 34.
Helianthus annuus
Helianthus divaricatus
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.)
One of the earlier flowering perennial Helianthus, H. divaricatus resembles the tetraploid H. hirsutus but differs by its usually glabrous and often glaucous stems, sessile or subsessile leaves, and smaller reproductive organs (disc corollas, paleae, cypselae). Plants from the Ozark region of Arkansas have larger leaves and heads and may represent a polyploid form of H. divaricatus. Natural hybrids with H. microcephalus have been named H. glaucus Small (D. M. Smith and A. T. Guard 1958). Hybrids with other species differ from H. divaricatus in having short but distinct petioles, hairy stems, leaves with more rounded bases, and primary lateral leaf veins diverging in a subopposite manner distal to bases, rather than being strictly opposite and basal.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
KS Wildflowers, 
LA Plants, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria, 
SW CO Wildflowers, Turner Photog. 
WildflowerSearch
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USDA Plants Database- LBJ Wildflower Center
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