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Weed Identification

common sunflower



Scientific Name

Helianthus annuus

Other Common Names:

wild sunflower
annual sunflower

Synonyms (former Scientific Names):

Helianthus lenticularis
Helianthus aridus


Wild sunflower can complete its life cycle in as little as 60 days and can get from 8-15 ft tall. These plants tolerate heat and drought, but perish after the first frost. Blooms first appear in early summer and continue into early fall.


When young, the seedlings are bright green and the width is double the length. Large, rough-hairy oval to heart shaped leaves; lower leaves opposite and chordate, the upper, smaller and narrower. The stems are sometimes branched, and the hairs on the stem are coarse. Mature leaves can be 3 or 6 inches (8-15 cm) to 1 foot (30 cm) across, usually with rough hairs.

Identifying Characteristics

The flower heads start out facing the east in the morning, and end up facing the west at the end of the day, following the sun.

Flower Seed Head

There will be 1-12 flowers that bloom during the summer to early fall. Large, gold, red-brown and yellow flower heads 3-12 inches across. Most have yellow ray florets and purplish brown disk florets. The ray florets of sunflowers are sterile, and only the disk florets produce seeds.

Seed Fruit

The seed can be seen in the center of the flower very easily. Fruit is a dry, dark casing with white stripes enclosing a white seed; flattish but plump.

Where Found

Prairies and dry, open areas, and is sometimes a weed in cultivated fields and pastures.

Growth Habit

upright and nonwoody

Thorns or Spines

not present

Approximate Flower Diameter


Dominant Flower Color


Flower Symmetry

radial symmetery
bilateral symmetry

Leaf Hairs

has hairs

Leaf Arrangement


Leaf Margin


Leaf Structure


Leaf Stalk

shorter than leaf

Stem Hairs

has hairs

Stem Cross Section

round or oval

Milky Sap

not present

Root Structure


Life Cycle

summer annual



Plant Type