Field of sunflowers. The sunflower (Helianthus annuus) originated in the USA, was introduced to Europe in 1596, and is now grown widely as a garden ornamental or for its seeds which yield an edible oil. Flowers may often reach 30cm in diameter and have a characteristic spiralling pattern of florets. An annual species the sunflower can grow from seed to several meters tall in just a few months. The tallest recorded example measured 7.76 metres.