  helianthus annuus, the common sunflower, is an annual species of sunflower grown as a crop for its edible oil and edible fruits (sunflower seeds). this species of sunflower is also used as bird food, as livestock forage (as a meal or a silage plant), and in some industrial applications. the plant was first domesticated in the americas. wild helianthus annuus is a widely branched annual plant with many flower heads. the domestic sunflower, however, possesses a single large inflorescence (flower head) atop an unbranched stem. the name sunflower may derive from the flower's head's shape, which resembles the sun, or from the false impression that the blooming plant appears to slowly turn its flower towards the sun as the latter moves across the sky on a daily basis. sunflower seeds were brought to europe from the americas in the 16th century, where, along with sunflower oil, they became a widespread cooking ingredient. == description == thumb|left|head displaying florets in spirals of 34 and 55 around the outside the plant has an erect rough-hairy stem, reaching typical heights of . the tallest sunflower on record achieved . sunflower leaves are broad, coarsely toothed, rough and mostly alternate. what is often called the "flower" of the sunflower is actually a "flower head" or pseudanthium of numerous small individual five-petaled flowers ("florets"). the outer flowers, which resemble petals, are called ray flowers. each "petal" consists of a ligule composed of fused petals of an asymmetrical ray flower. they are sexually sterile and may be yellow, red, orange, or other colors. the flowers in the center of the head are called disk flowers. these mature into fruits (sunflower "seeds"). the disk flowers are arranged spirally. generally, each floret is oriented toward the next by approximately the golden angle, 137.5Â°, producing a pattern of interconnecting spirals, where the number of left spirals and the number of right spirals are successive fibonacci numbers. typically, there are 34 spirals in one direction and 55 in the other; on a very large sunflower there could be 89 in one direc
Agriculture_in_Mesoamerica Annual_plants Butterfly_food_plants Edible_nuts_and_seeds Energy_crops Flora_of_North_America Flowers Garden_plants Garden_plants_of_North_America Helianthus Honey_plants Phytoremediation_plants Plants_described_in_1753 Plants_used_in_traditional_Native_American_medicine