plantvillage.psu.edu/topics/sunfl...nflower/infos
Sunflower, Helianthus annuus, is an herbaceous annual plant in the family Asteraceae, grown for its seeds. The plant has a thick, hairy, erect stem which gives rise to a large flower head. The plant has large, broad lower leaves which are oval and arranged alternately on the stem and smaller, narrower upper leaves which are attached individually to the stem. The flower head is a large disc reaching 10–30 cm (4–12 in) in diameter which is made up of 16–30 individual florets which are yellow-gold in color. The outer florets are sterile and produce the outer petals of the flower head, while the inner florets will mature into the seeds in the central disc. Sunflowers are annual plants, harvested after one growing season and can reach 1–3.5 m (3.3–11.5 ft) in height. Sunflower may also be referred to as girasole and originates from North America.