Appearance

Helianthus annuus is a coarse, hairy, leafy, fast growing annual that grows from 5-10 ft (1.5-3 m) tall on stiff upright stalks. It is native to dry plains, prairies, meadows and foothills in the western U. S., Canada and northern Mexico.

Foliage

The leaves are large, ovate to triangular, sandpapery and up to 12 in (30.5 cm) long.

Flowers

The 3-6 in (7.6-15 cm) wide sunflowers with orange-yellow rays and brown to purple center disks. Flowers bloom through the summer.

Fruit

The disk flowers give way to the familiar sunflower seeds. The fruits are achenes which contain one seed.

Ecological Threat

H. annuus is native to North America, although Iowa lists it as a State Noxious Weed. It is also considered a weed in many agricultural areas. It is grown commercially for the seeds and the oil extracted from them, both for human consumption and as a wildlife food. H. annuus contains the world's second most important and valuable oil seed. (Coconut oil comes first.) The seeds contain 35-40% oil. They are high in polyunsaturated fat and contain no cholesterol. The seeds are a good source of protein, starch and calories.

Selected Images

Maps

Invasive Listing Sources

• Iowa Noxious Weeds

References