Common sunflower

Encyclopedia Article

Common sunflower                                 Helianthus annuus L.

Family:   Asteraceae (Composite family)      
Life cycle:   
Native status:  Native to North America
Habitat:   Crop fields, disturbed areas                                    

General description:   Erect plant up to 14 ft tall with coarse stems.  Lower leaves heart-shaped, upper ovate to lanceolate; margins toothed to entire.  Numerous ‘sunflower’ heads produced up to 6” wide.

Key ID traits:  Rough stems and leaves, leaves heart-shaped, triangular or lanceolate with long petioles.

Similar species:  Common cocklebur seedling resemble those of common sunflower, but sunflower has small ovate cotyledons whereas cocklebur has large lanceolate cotyledons. Stems of cocklebur have dark spots, whereas sunflower's are hairy.

Miscellaneous:  There are numerous native Helianthus species, but Helianthus annuus is the only one with weedy tendencies.  When sunflower was added to the noxious weed list, a Kansas legislator jokingly proposed opening a hunting season for the goldfinch (common sunflower is the Kansas state flower, the goldfinch is Iowa’s state bird).

seedling with ovate cotyledons
Seedling with ovate cotyledons

erect plant with large, heart-shaped leaves
Erect plant with large, triangular or heart-shaped leaves.


Triangular leaves with long petioles.

Erect, branched growth habit with multiple flower heads


The sunflower (composite) head has two types of flowers. The petal-like structures are ray flowers, the dark flowers in middle are disc flowers. On sunflowers the ray flowers are sterile.

Common sunflower on edge and within corn field