Information on Helianthus Annuus

Sunflowers are part of the aster or daisy family.

Helianthus annuus or common sunflowers are native to dry, open areas of the United States and Canada. They were widely cultivated in North America before European settlement, according to the Lady Bird Johnson Wildflower Center.

Identification

Common sunflowers grow between 1.5 and 8 feet tall. Their coarse hairy leaves grow approximately 8 inches long. They have thick, hairy light-green or reddish stems topped by large, showy, daisy-like flowers. The flower centers produce edible seeds that mature in the fall.

Cultivars

Sunflowers are available in a variety of cultivars, according to Floridata. The Italian White cultivar produces 4-inch flowerheads with white petals and black centers, while the Autumn Beauty cultivar grows approximately 5 feet tall and produces reddish-brown, yellow or bronze-colored rays. The Russian Giant cultivar grows over 12 feet tall and produces bright yellow flowerheads that grow as wide as a foot across.

Considerations

Common sunflowers prefer full sunlight and slightly dry soil. They thrive in a variety of different soil types, but often do well in soils with a high gravel or clay content, according to the Illinois Wildflower Info website. They propagate easily by seed. Sunflowers are tolerant of drought, but they die after the first frost. Sunflowers release plant chemicals that kill off competing vegetation.

References

• Lady Bird Johnson Wildflower Center: Helianthus annuus (Common Sunflower)
• Floridata: Helianthus annuus
• Illinois Wildflowers Info: Annual Sunflower