Helianthus annuus (Sunflower)

Well known for their iconic inflorescence, Sunflowers are very hardy annuals native to North America. They grow rapidly in most areas, often outcompeting native or invasive “weeds”. They tolerate most soils and survive droughts very well due to their extensive taproot and persistent lateral roots. Sunflowers are the most significant crop grown today that are native to the new world.

Helianthus annuus (Sunflower)
Deciduous: yes
Hardiness Zones: 2-11
Height: 1-3 meters (3-10 feet) tall, smaller varieties to 1 meter (3 feet) tall, giant varieties to 4.5 meters (15 feet) tall
Diameter: 45-90 centimeters (18-36 inches) wide
Growth Rate: rapid
Age: annual
Root System: taproot to 3 meters (10 feet) tall, spreading lateral roots near soil’s surface
Family: Asteraceae
Subspecies: many colors (red, orange, yellow) available; ssp. lenticularis (wild sunflower), ssp. annuus (weedy wild sunflower), ssp. macrocarpus (edible seeds),
‘Mammoth Russian’ (giant), ‘Pole Star’ and ‘Jupiter’ (moderate size), ‘Advance’ and ‘Sunset’ (dwarf)

Tolerates: herbivores (deer, rabbits), dry soils, drought, fungi, limestone, frost, very acidic to very alkaline soils, poor soils, wet soils, light/sandy soils, viruses,
competing weeds, air pollution
Problems (major): none
Problems (minor): strong winds (for taller specimens), rust, leaf fungal spots, powdery mildew, caterpillars, beetles
Poisonous: presumably no, seeds edible raw

Soil requirements: tolerates dry and wet soils of any pH, limestone, and light/sandy soils
Air requirements: tolerant of poor urban air conditions (air pollution)
Watering requirement: somewhat low to moderate
Sun requirement: requires full sun

Leaf shape: ovate to triangular, opposite or alternate
Leaf size: up to 30 centimeters (12 inches) long by 20 centimeters (8 inches) wide
Flower structure: large inflorescences to 15 centimeters (6 inches) in diameter, bright yellow rays, brown/black flowers in the center, emerge at the tops of stems, may droop, terminal
Flowering frequency: July and August
Seeds: 4-pointed, elliptical, white with black stripes, to 2 centimeters (1 inch) long, achenes
Bulb/tuber: neither
Monocot/Dicot: Dicot
Annual/Biennial/Perennial: annual

Notable characteristics:
These are very hardy, quick growing annuals with magnificent terminal inflorescences. These are grown as a crop for feed and their seeds and in gardens for their
ornamental value.

The oil from sunflower seeds is used for a variety of culinary uses. The kernels/seeds are eaten either raw ot baked by humans, birds, and other animals. The seeds
have been used in folk medicine as cures for an extremely wide range of ailments.

Sources used:

A dwarf variety, the inflorescence

A dwarf variety, with only a few leaves due to its miniature size

All of the images provided were taken by me. They may be used for educational/informational purposes only, provided that this article/online journal is appropriately cited first.


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