Helianthus L.

	Helianthus annuus: stem

sunflower

sunflower

Most commonly cultivated

Helianthus annuus L. (over 50 cultivars)

Other species

H. angustifolius L.

H. debilis Nutt.

H. decapetalus L.

H. maximiliani Schräd.

H. salicifolius A. Dietr.

North America to Central America.

Broadly ovate to heart-shaped, dentate, usually alternate leaves; flowers (florets) in large, radiate heads; head subtended by saucer-shaped to hemispherical involucre of hairy, subequal to imbricate phyllaries in 2 or more series, with caudate apices and ciliate margins; ray florets sterile; central disc large, dark-colored, receptacle scaly; pappus of 2 scale-like awns, sometimes with additional, smaller scales. Hairiness pervades throughout (leaves, stems, phyllaries, ovary, disc florets, and style pubescent).

Heads generally 5-20 cm in diameter, with central disc usually large relative to ray florets; heads usually solitary, although stems sometimes branched; ray florets are seen in many variations of yellow to orange, in some cultivars they are red and/or multicolored; disc florets usually brown, yellow, or purple; heads usually single or semi-double, less often fully double; some cultivars are pollenless.

Egypt, South Africa.