Flower head
A tight disc of many tiny flowers that looks and works like one big flower, as in a daisy.
Also: capitulum, composite flower
A sunflower is not one flower. It is a flower head, or capitulum: hundreds of very small flowers, called florets, packed onto a flat base and ringed with green bracts. The whole thing behaves like a single bloom for a visiting bee. This design belongs to the daisy family, which includes marigolds, chrysanthemums, dahlias, gerberas, zinnias and asters. Most heads have two kinds of floret: strap-shaped ray florets round the edge and small tubular disc florets in the centre.