How to Manage Pests

Identification: Weed Photo Gallery

Sunflowers

Scientific name: Helianthus spp. (Sunflower Family: Asteraceae)

Click on image to enlarge

Sunflowers are large, rough, hairy broadleaf plants with large yellow flower clusters. They may be summer annuals or perennials. When mature, the center or disk flowers hold scores of seeds that are very attractive to birds. Eleven species of Helianthus are found in California and some are classified as noxious.

Seedling

Cotyledons (seed leaves) are bright green and two to three times longer than they are wide.

Mature plant

Stems are single or branched depending on the species. They are thick and covered with coarse hair. Leaves are spade shaped and range from about 3 to 6 inches (8-15 cm) to nearly 1 foot (30 cm) across and generally have rough hairs.

Flower

Flower clusters are composed of a dark center (disk flowers) surrounded by a halo of yellow to orange flowers that look like petals (ray flowers).

Fruit

Fruit are single-seeded (achenes) and resemble those of commercial sunflower seeds.

Reproduction

In some species propagation is by seed only and in other species, by seed and creeping roots.

More information

• Broadleaf ID illustration
• Calflora's distribution map
• See UC IPM's Pest Management Guidelines for agricultural information