Magnoliophyta Subdivision: Eudicots Class: Asterids Order: Asterales Family: Asteraceae Subfamily: Helianthoideae Tribe: Heliantheae Genus: Helianthus Species: H. annuus Description What is usually called the " flower " on a mature sunflower is actually a " flower head " (also known as a "composite flower") of numerous florets, (small flowers) crowded together.