What is Sunflower?
Sunflower, Helianthus annuus, is an annual grown for large flower heads and oil-rich seeds. Its apparent single bloom contains many small flowers.
Botany and life cycle
1. Identity and native range Helianthus annuus belongs to Asteraceae and originated in North America. Oilseed, snack and ornamental cultivars differ. 2. How to recognize it Broad rough leaves, stout stems and a composite head stand out. Yellow ray florets surround many tubular florets; dry fruits develop in the center. 3. Flowering and reproduction Bees and other insects pollinate florets. Young buds may track light, but mature heads do not necessarily follow the sun all day.
Ecology, cultivation and uses
4. Habitat and ecology Full sun and adequate water support growth. Flowers feed pollinators and ripe seeds feed birds; monoculture has separate ecological costs. 5. Cultivation and care Sow after frost in sun. Tall varieties may need support. Manage water, nutrients and spacing for airflow. 6. Uses and cautions Seeds are used for food and oil. Packaged snacks vary in salt. The edible “seed” is botanically within a dry fruit.